Triangulating Your Genome

A How-To Example with MyHeritage

This blogpost will walk you through the steps to Triangulate your shared DNA segments at MyHeritage – creating a Triangulated Genome. You can use this same process at 23andMe and roughly the same process at GEDmatch and FTDNA. Disclaimer: This Process takes time (I estimate about 120 hours); but once you are done, you have a powerful tool.

The objective of Triangulating Your Genome is to determine 300-400 Triangulated Groups (TGs), adjacent to each other, covering your 44 to 46 Chromosomes from beginning to end. These TGs group almost all your shared DNA segments, cull out most of the smaller false “shared” segments, and identify recombination/crossover points where your DNA shifts from one Ancestor to another. Each TG will represent one segment of your DNA (equivalent to a phased segment), which came from a specific Ancestor, down a line of descent to one of your parents and then to you. This is segment-ology in a nutshell.

The Process

I will describe this process briefly and then in detail, using MyHeritage as an example.

Very brief version – group segments per the Triangulated Segment icon at MyHeritage (see details below). The Main Steps are basically the same for 23andMe, GEDmatch or FTDNA.

Overview – The Main Steps

1. Download the Segments from MyHeritage

2. Set up the Spreadsheet (headers, set a threshold to cull out small segments, add columns, etc.)

3. Group the Segments (the main, long, process – estimated time: 120 hours)

      a. Note any known Shared Match relatives as you go – they help later.

4. Summarize the groups (add a header row and ID# for each group, etc.)

      a. Assign partial TG-ID: Chr# plus A-Z (depending on Start location)

      b. NB: At this point you should have 300-400 groups. Each group represents one segment of your DNA from a specific Ancestor. This is very powerful information and is useful in its own right. Assignment, in the next step, makes each group even more powerful.

5. Assign groups into TGs – genealogy, logic and/or judgment required

      a. Assign each group to a maternal or paternal side.

      b. Use Genealogy; logic; “spanning” segments; TG “linkage“; ethnicity, etc.

      c. NB: Not all TGs may be determined.

  6. Enjoy

In the following sections I will describe each of these 5 steps in more detail.

Section 1 – Download the Segments

Log into MyHeritage and click on the DNA tab.

A menu comes down – click on DNA Matches to get:

Select the kit you want to use – for this example I will use my father’s kit, which I had not Triangulated at MyHeritage before.

Here is my father’s page – note 14,225 DNA Matches. Click on the 3-dot ellipsis on the right.

From the menu select: Export shared DNA segment info for all DNA Matches. Note the little Triangulation icon.

You should get a pop-up with a note that the spreadsheet will be mailed to you in a few minutes:

Section 2 – Set Up the Spreadsheet

Here is, generally, what your spreadsheet will look like:


1. Save this CSV file as a spreadsheet. I normally include a date in the title (e.g. JVB MH Segs 20201225) I tend to save various versions during this whole process – as backups.

2. The headers are: DNA Match ID [you’d only need this in case of 2 Matches with the same name]; Name [base person with all the Matches – usually you, but in this case my father, James Vincent Bartlett]; Match name [name of each Match – I reduced the width of this column to hide the names for privacy]; Chromosome; Start Location; End Location; Start RSID; End RSID [these RSIDs identify a SNP – useless info to me]; CentiMorgans; and SNPs.

3. Make a backup copy of this spreadsheet – just in case…

4. Delete the Start RSID and End RSID columns.

5. Move the DNA Match ID column to the far right side [out of your way].

6. Insert two blank columns on the left side; and 10 columns to the right of the SNP column.

7. Divide Start and End Locations by 1,000,000 – changing them from bp to Mbp. This will not change the accuracy of anything (all the digits will remain), but it will make it much easier to analyze and deal with these numbers. [My process for this: create two blank columns next to the Start and End columns – let’s say Start is column F; End is column G; the new columns are H and I; and the first row under the header is 2. Then in cell H2, enter: +F2/1000000. Then copy this cell [drag it] to column I. Check to ensure the numbers in H and I are the same numbers in F and G divided by 1,000,000. Now copy cells H2 and I2 to the bottom of the spreadsheet. Next highlight all these numbers: H2 to the last number in row I. Copy that data (Cntr-C). Move the cursor to F2 and right click on it. From the menu, click on the Paste Special icon with 123 in it (that means copy the result, not the formula). All of the data in columns F and G should now be in Mbp, and columns H and I can be deleted.]

8. Sort the spreadsheet by CentiMorgans.

9. Select a cM threshold, and remove [or physically separate to the bottom of the spreadsheet – out of your way] all segments under your threshold. In my case I used 10cM. This removed about 2/3 of the segments, leaving a group with larger cMs that I would be working with. A lower threshold of 6cM or 8cM will greatly increase the time for this process – not recommended. A higher threshold of 12cM or 15cM or even 20cM will shorten the time, but will leave more gaps. Your choice! By keeping these smaller segments separated at the bottom of the spreadsheet, they are still available in case you want to use some of them later. If you delete them, that’s OK – you can always retrieve them from a backup copy.

10. Type in Header titles*: Hd (for headers); Co (for Company); ID#; Par (for parent initial); Sib (for sibling initial); Ch (for children initial); Czn (for close cousin initial); TG (for Triangulated Group); G2 (for generation 2: parents – the “side”); CA/Remarks (for Common Ancestor or any other remarks you want to save). See the example below. *Each of these will be explained more fully, later.

11. Add in “header” rows for each Chromosome – see example below. This is just a visual separator that helps separate the segments by chromosome.

12. Now sort the “over-10cM” part of the spreadsheet by Chr and Start. Remember to highlight the full rows whenever sorting to keep the data in each row with the correct Match.

Resulting spreadsheet:


1. I’ve inserted MH (for MyHeritage) in the Co column. This is not important if you will only use data from one company. Eventually I will add data from GEDmatch, 23andMe, and FTDNA, and I want to be able to sort by company from time to time.

2. There are 2 columns between ID# and Par – these are “extra” and sometimes come in handy when grouping – specifically when one group overlaps another group.

3. The Chromosome header row provides a visual demarcation between chromosomes.

This Chr/Start sort puts all overlapping segments adjacent to each other in the spreadsheet. NB: some of these will be on your paternal side; some will be on your maternal side; and a very few (usually under 15cM) will not Triangulate with either side, indicating they are probably false. Under the next section you will form groups, and each group will be on one side or the other. We cannot know, just by grouping, which side they are on; but we do know all the segments in a group will be on only one side.

Section 3 – Group the Segments

This part is hard work. It’s not difficult – the grouping process is fairly straightforward. But I cannot sugar coat it – it is tedious. I used a stop watch to time each chromosome, and I got better (more Mbps grouped per hour) as I progressed through the Chromosomes. In total it took me 120 hours – a table of hours is at the end of this section.

You can start anywhere. I started at the top of Chr 01 and just worked down (I knew I was going to do the whole thing). In hind sight, you might want to start with a medium or small Chromosome, to develop your “rhythm” – to get your “sea-legs” as we say in the Navy. The two ends of a chromosome are often the hardest – so you may want to just start in the middle of one. Later in this blog post I’ll include some other observations. But for now, just start

Pick a Match at, or near, the top and put a one in the ID# column. This is the base Match for a while.

I picked “Don…”, the third Match down, because the segment started where the other’s did, but was a little longer. This segment was more likely to Triangulate with others further down the list, whereas the top Match, “vicki”, ending at 5.6Mbp, may not overlap enough with many of the others. It’s really a matter of efficiency. In the end, we are going to “touch” all of the above-threshold segments in the spreadsheet. As you’ll find, it’s easier to get set up with one base Match and “touch” as many as you can, before you have to regroup and start over with a new base Match. NB: Once a Match-segment is “touched”, and added to a group, it does not need to be selected again later. However, use any order that suits you.

So now “Don” is our base Match. Next we search/select Don at MyHeritage (we’ll use his full name, and check the cMs of the shared segment – just in case there there is more than one Match with the same name (I found about a dozen such cases).

This is where two monitors really helps. Put MyHeritage (from the internet) on one screen and your  segment spreadsheet on the other screen. From your spreadsheet, copy the Match name cell for “Don…” which has the full name, exactly how MyHeritage has it. Then paste this into the search box at MyHeritage.


1. At My Heritage, my father’s name is circled top left – it’s his genome I am Triangulating

2. Don’s name info is copied into the search box – “Don” is the base Match this time

3. Next: See Downward Arrow and Click on the name; or click on the magnifying glass in the Search box to get a list of Matches per the search criteria. Often the name you want will be the only Match listed. However, sometimes multiple options will be listed and you have to select the correct one (usually the amount of shared DNA will help). Match names like Thomas Jones may return hundreds of Matches – in that case, I punt – and go back to the spreadsheet and select a different Match as the base.

4. Once you’ve selected the correct Match, click on the colored link: Review DNA Match. This will call up a long page focused on that Match. Scroll down past Theories, Smart Matches, Shared ancestral surnames, Shared ancestral places, etc. until you get to the section called: Shared DNA Matches. See below:


1. This is the top of the list of 168 Shared DNA Matches between my father and Don. The top two Matches are a close relation to Don and a close relation (me) to my father. Please note the “triangulated segment(s)” icon to the right of these two Matches. In this case Don shares two segments with my father, so I need to click on the icon to insure each Shared DNA Match is sharing the DNA segment at the beginning of Chromosome 1 in the spreadsheet. Scroll down the Shared DNA Matches at MyHeritage, noting which ones share a triangulated segment on Chr 1, and note them with a digit in the ID# column:


1. Don and 5 other Matches are shown here as sharing a Triangulated Segment with my father. Indeed, Don matches my father, and each of the Matches also match my father and Don. This is Triangulation in each case; and as a group, they form a Triangulated Group (TG).

2. At the bottom of the first page of Shared DNA Matches (each page has 10 such Matches), keep tapping on “Show more DNA Matches”, until you get to the bottom of the list. The Shared Matches are roughly listed in by total amount of shared cM, so by going to the end of the list you will pick up the shortest Shared Matches. I think this method is the most efficient in “touching” all the Match-segments.

I then picked “Virgi” as the next base Match; copied that name from the spreadsheet cell; pasted it into the search box at MyHeritage; selected the correct “Virgi” from the list of Matches that came up; clicked the “Virgi” Review DNA Match link; scrolled down the resulting pages; and reviewed the Shared DNA Matches between my father and Virgi who had a Triangulated Segment icon. I noted all of them with a “2” in the ID# cell.


1. It’s easy to see that the group with ID# 1 and the group with ID#2 overlap the same area on Chr 1 – one of these groups is on my father’s paternal Chr and the other is on his maternal Chr. At this point we cannot tell which is which – more on that in Section 4.

2. I then tried Match “John” and drew a blank – “John” did not have any Shared DNA Matches who had a Triangulated Segment icon for Chr 1.

3. Next I tried “blai” as the base, and “blai” had some icons with Matches who already had a 2, and some new Matches. So we now have:

I now paused to re-sort this part of the spreadsheet – I sorted by ID# and Start. This moved “John” to the top (out of the way – as almost certainly a false segment); and clearly showed the ID#1 and ID#2 groups:


1. The color coding in this figure is just to highlight the two groups. I do not do this in actual practice – I let the sorted ID#s speak for the groups.

2. Select the next, ungrouped, Match-segment, “Nanc”, and repeat the process.

3. For ID#, use the numbers 1 to 9 first, then the letters a to z – they will all sort in order.

Grouping Mantra: Select a base – group segments – repeat…

A quick summary of these steps:

1. Select the next base Match in your spreadsheet

2. Copy the Match name

3. Paste the Match name into the search box at MyHeritage – and execute the search

4. Select the Match from the ones listed and click on “Review DNA Match

5. Scroll down the resulting page to Shared DNA Matches

6. Look for Matches with the Triangulated segments icon

7. Verify it’s the spreadsheet segment of interest (same cMs as in spreadsheet)

8. Type in the ID# character (1 to z) in the spreadsheet

9. Continue down the spreadsheet per steps 6-7-8, until the last Shared DNA Match

10. Repeat from #1.


1. Generally pick the next Match in the spreadsheet as the next base. However, if it is a common name, or if it’s a very small segment, or if that Match turns out to share several segments, feel free to select another Match, near the top of the list, as the next base.

            – this makes the process go faster

            – a skipped Match will often show up as Triangulated later in the process

2. At the end, you can always go back and pick up any “stragglers”. These “stragglers” will usually be smaller segments, which would usually have a very distant Common Ancestor – I’ve actually just abandoned some of these, and moved them to the bottom of the spreadsheet with the under-10cM segments.

3. Be careful with Matches with multiple shared segments – click on the TG icon to insure the TG segment agrees with the area you are working on. TIP: Note the total cM of the Match (with a TG icon) at MyHeritage – if that is the same cM as the Match in your spreadsheet – all is OK – you’re dealing with only one segment and it has to be the one you want. Most Match-segments will be like this.  

4. Some groups may be very small, and some may be very large. Many 10-15cM segments in a group may indicate a pile-up which is probably very distant – but at least you’ve grouped these segments to highlight that probability.

5. Don’t worry if the ends of some groups overlap the beginnings of other groups – the company algorithms cannot identify the crossover points precisely – these ends are fuzzy.

6. In my experience, MyHeritage Triangulation has never been incorrect. However, in some cases, segments that should Triangulate are not identified (a false negative), although those segments are almost always identified as Triangulating with other segments in the same group. I think imputation of SNPs is the culprit here. The main point is to put each Match-segment in a group (or cull it out as false).

7. In a few cases the picture got muddled. My best solution is to just skip over this area (these segments) and proceed further down the spreadsheet. Usually the bigger picture becomes clear, and you can return to the problem segments later.

8. Remember the objective of this exercise is to form 300-400 Triangulated Groups, spanning all of your Chromosomes. You do NOT have to adjudicate every shared segment to accomplish the overall goal. The 300-400 TGs are the prize – the important tools that will help you immensely.

Here is a summary of how long it took me to Triangulate each Chromosome:


1. I rounded my total of 115.9 hours up to 120 as an estimate for most folks. Hopefully you will have the advantage of using this blogpost to be more efficient than I was.

2. Chromosome 1 was a bear! But I was also working out processes and methods…

3. As noted before, you might want to start with Chromosomes 13 to 22. It’s a good feeling when you reach the end of each Chromosome;>j

Other observations about forming groups:

1. The Chromosome tips (Start and End of each Chromosome) usually have short TGs, and they are sometimes hard to figure out. For a few of these Chromosomes, I actually shifted to the middle of the Chromosome in the spreadsheet, and worked both ways. It doesn’t matter much as every shared segment has to be in one overlapping group or the other (or be false).

2. When searching at MyHeritage for Matches who have the TG icon:

      a. If there are only a few Matches (say under 10) in your spreadsheet which could overlap, then just look down the Shared DNA Matches at MyHeritage for the Matches with the TG icon. These few Matches will be easy to find in the spreadsheet – type the ID#.

      b. If there are many Matches in the spreadsheet which could overlap, I usually highlight those spreadsheet rows and sort them on Name. This way I can start with the Shared DNA Match name at MyHeritage (with a TG icon) and easily and accurately look down the alphabetized names in the spreadsheet to find the Match name – then type the ID#. [This advice may be more clear after you’ve tried finding some MyHeritage Matches in your spreadsheet.]

      c. At MyHeritage, skip over the Matches which show a total cM less than 10cM (or your threshold) – you’ve moved those Matches out of your grouping spreadsheet.

      d. Some Matches with a TG icon at MyHeritage may show, say, 18cM, but they aren’t in your spreadsheet. Upon inspection in the browser, the 18cM actually is two segments and the one you’re working on is below the threshold. Aaarrrrg! False alarm. Skip over that Match and continue looking for TG icons.

      e. These are my tips – or discover your own “most-efficient” way to find TG Matches at MyHeritage and then find those Matches in your spreadsheet to type the ID#.

3. From time to time, re-sort the Chromosome you are working on. Within a Chromosome, you can sort on ID# and Start location (they sort from 1 to z). This keeps the groups together and quickly shows you the remaining segments to work on.

4. Long segments. Sometimes a long segment will stretch beyond the bulk of the other segments in a group. This usually indicates a closer cousin, with a shared segment that spans across two (or more) segments. This is OK. Later, a segment in an adjacent group may also show a TG with the long segment. I tend to keep the groups separate, because they will probably come from different Common Ancestors down to you, through one closer Ancestor. The long segment is an important “tell tale”, indicating both groups are on the same side, and closely related.

5. Most “tell tales” will come from known close relatives. These are parents, children, siblings, avuncular, close cousins and Theories of Family Relativity (ToFR) that you agree with. Parents, avuncular, cousins and ToFR are particularly useful in identifying the side of a TG. Children and siblings tend to share long segments on one side or the other – usually through several TGs and sometimes over an entire Chromosome. Use the Par, Sib, Ch, and Czn columns in the spreadsheet and type in initials (or other identifier) for these known relatives as you find them as Shared DNA Matches with TG icons at MyHeritage (check the browser to ensure they share on the right segment). I note a Match ToFR in a spreadsheet column for Common Ancestor/remarks. These will help you later.

6. Even with a lower threshold of 10cM, some of the 10-15cM segments don’t always match others as they should. I note that MyHeritage uses imputation to add “most probable” SNPs, in order get larger, more complete segments. But I recall that they don’t use these inputed SNPs when they declare TGs – so even though there is an overlap, sometimes MyHeritage won’t indicate a TG. As a result, not all overlapping segments in a group with show with a MyHeritage TG. I got used to it. After all, every shared segment has to be from one parent or the other (or be false). So if a segment shows as  TG with several others, it’s probably true, even if it doesn’t match every segment it “should” match. If you get frustrated with a Match-segment in your spreadsheet, just code it ID# 0. You can ignore it now, or forever. It saves time to “skip over” problem segments.

7. MyHeritage appears to be throttling the Shared Match list after an hour, or so. The “Show more DNA Matches” sticks on the timer and doesn’t show the next list, and/or the next page just hangs up looking for TGs – in either case, you cannot find any more TGs. Options:

      a. Click on your browser refresh icon (top left).

      b. Use the back arrow, and try a different Match.

      c. Turn MyHeritage off; and then back on.

      d. Try again 8-12-24 hours later… I was always able to start fresh the next day.

      e. Maybe just be content with working on this project an hour a day.

8. Order is not a factor – you can literally work any area of your spreadsheet you want, in any order you want. But the objective is to cover the whole genome eventually.

9. Extra Credit – determine the number of segments: In the beginning, before sorting out the small segments from your spreadsheet, add a column called “Seg”. Then sort the entire spreadsheet by Match name DNA Match ID. Put a 1 (the number one) in the “Seq” column for the whole spreadsheet – most of your Matches, by far, will only share 1 DNA segment with you. Then scroll down the whole spreadsheet and change the 1 to the number of segments each Match shares with you. Yes – this is tedious; but this information (number of segments a Match shares), is very helpful in selecting a base Match, or even understanding that there are multiple segment. However, this is NOT a required step for the overall process.

10. Don’t get discouraged – this whole process gets familiar and easier as you gain experience. Take frequent breaks. The end result is worth it.

Section 4 – Summarize the Groups

When you are done grouping all the segments, take a well earned break! The tedious part is over. This section is easy and a little fun…  We are going to insert a header row for each group. We still don’t know which side (maternal or paternal) each group is on, but we do have the Match-segments in groups. I estimate you will get about 300-400 of them.

See the figure below:

In this case, I inserted a new row just above ID#9 in Chromsome 8. I like to use a highlight color. For these “group” rows, add TG in column A; and TG in the Match name column; type the Chromosome number in that column; and the ID# in that column. In the Start Location column type in a number just a little bit smaller than the first segment  – I typed in 64.0 over 65.0 for ID#9 and 77.0 over 77.2 in ID#a. The idea is that I can sort the spreadsheet by Chr, ID# and Start and always come back to this list with all the Match-segments sorted in their respective groups.

Repeat for all 300-400 groups. NB: There will always be two groups that start at the beginning of each Chromosome – one for each side. For each of these group headers, use .001 for the Start location – this will sort before any Match-segments and after the Chromosome header (which Starts at 0.0).

Now we can also assign the first three characters to name this groups as TGs.

      – The first two characters are the Chromosome number: 01 to 23

      – The third character is a letter indicating where the group starts:

            A for 0 to 9.9Mbp; B for 10.0 to 19.9Mbp; C for 20.0 to 29.9Mbp; etc.

Here is an example:

In the next section we can start assigning the TGs to sides…

Section 5 – Assign Groups into TGs

This is the final section. After all of the tedium of grouping segments, we now come to assigning these groups to a maternal or paternal side. As mentioned before, each group represents part of your DNA – on one Chromosome or the other. Each group is DNA from your maternal side or your paternal side. The segment data, by itself, doesn’t provide a clue. We cannot assign a side without additional information. We need to use genealogy.

The main method is to use known relatives. If you’ve tested at least one parent, that is gold at this point. You can pretty quickly determine all the shared segments which include that parent, and the remainder would be with the other parent. I used that method to Triangulate my own genome – I have my father’s atDNA, which was a huge advantage. But now, I’m working on Triangulating my father’s genome – his parents, and their generation, are long since gone. So, in this case I have to rely on known relatives. And we can use logic in some cases – more on that later.

There are some workarounds… For instance someone who is half English or half Ashkenazi Jew or half Scandinavian or half Asian or half African… we might be able to tell from the Match names (or Ancestors) in each group which side they were on. It’s a stretch, but perhaps one parent has New England ancestry, and the other parent has Colonial Virginia ancestry… We’d need to really dig into the Trees of many Matches in each group to tease this information out.

I like using Ahnentafel numbers, so I assign the number 2 for the paternal side, and the number 3 for the maternal side. Alternatively, use P for paternal and M for maternal.

In the following example, I have a close paternal cousin of my father – John. Wherever I found John, I could add 2 (for paternal side) to a column I called G2 (for the second generation, which are the parents).

I know that the ID# 9 group he is in must also be paternal (they all share the same Common Acnestor). I can add a 2 to the TG ID and assign that TG ID to each segment in that group:

All of the shared segments in group ID# 9 are now assigned to TG 08G2 and G2 = 2 (paternal side). This 2 on the paternal side is important because, later, I can separate all my segments into paternal and maternal sides, and very easily see how they are adjacent (or not) to each other. They should be adjacent to each other, and this kind of a sort will highlight any gaps.

Next, we will use some logic. TG 08G2 ends in the 76-78 range (discounting close cousin John’s long segment ending at 90.6 – which close cousins often overlap to the next TG). Group ID# a starts at 77.2, which looks like a good “fit” – a little better than the 82 to 96.9 range in Group ID# b. So, I’m going to conclude that ID# a is a continuation on the 2 – side.

Continuing with this logic, group ID# b clearly overlaps ID# a (side 2) by a lot. So it must be on the other side – side 3. So we now have TG 08I3.

We actually have several different ways to make these assignments:

1. Common Ancestors:

      – The best way to make assignments is with known close relationships which tell us which side a group is on. Parents, aunt and uncles, and close cousins are strong indicators.

      – MyHeritage also offers Theories of Family Relativity (ToFR). My experience with them is mixed – some are clearly correct (they agree with my 46 years of research); some are completely bogus. So, heed the correct ToFRs, and make assignments to a side accordingly. Ignore the bogus ToFRs.

      – Also use Common Ancestors with Matches which you work out on your own and are confident about.

2. TG “Fit”: Examine the rough Ends of TGs and see where they fit with the Starts of subsequent groups. All of these groups and TGs have to fit together somehow. None can significantly overlap any others on the same side.

      – However, allow close cousins with long shared segments to overlap.

3. Siblings and Children: Not illustrated here are the use of siblings and children. They tend to share very long segments on the same side – spanning several groups or TGs. So, also follow those patterns, which “tend” to stay on the same side from TG to TG.

4. Ethnicity and Geography: As previously discussed, you can also use ethnicity in some cases. You can even make a case for geography – if one side has some unique geographic roots that set it apart from the other side.

5. Other companies & Matches: I should also make the case for Matches from other companies. I’ve done most of my father’s genome, and now I’m reviewing his Matches and known Common Ancestors from FTDNA and GEDmatch and figuring out most of my father’s remaining TGs. The genome we work with (usually our own, but in this case my father’s) is fixed – the recombination crossovers are determined before birth, and don’t change. Although the companies may test a different set of SNPs, the 300 to 400 Triangulated Groups should stay the same. The start and end of each TG may be a little fuzzy, but the bulk of the TG still comes from a specific Ancestor, down a line of descent to one of your parents to you. Don’t worry about the fuzzy ends – think about the thousands of SNPs in a TG coming from an Ancestor.

6. Painting and Clustering: If you use DNA Painter or Clustering and determined a side for some of your Matches, use that information.

Other observations:

1. Double up on all the Chromosome headers – there needs to be two for each Chromosome – one paternal (put a 2 in the G2 column) and one maternal (put a 3 in the G2 column).

2. Something I thought about, but haven’t tried, yet. Set the threshold at 20cM and Triangulate those segments fairly quickly (you would skip over a lot of Matches with TG icons who shared less than 20cM). Then re-sort the full spreadsheet and set the threshold at 15cM – then re-sort the 15cM+ spreadsheet by Chr and Start. This has all the segments in order, but the paternal and maternal sides are comingled with the new 15-19.9cM segments. These new segments should be easy to Triangulate other segments already identified with TG IDs. I predict some of the larger TGs will be subdivided in this process. Then drop the threshold to 10cM and repeat. That would take 3 passes through the whole genome, but it may go faster than by starting with a 10cM threshold. Maybe I’ll try my brother’s MyHeritage kit that way…

Section 6 – Enjoy

This in a MAJOR MILESTONE in Genetic Genealogy. Now that you’ve put in the work to create 300-400 TGs that cover your genome, enjoy the benefits of this great tool!

1. All new shared segments (from any company) should quickly and easily fit into an existing TG. You have the framework for organizing all your Match-segment data.

2. Each TG comes from a Common Ancestor – even ones behind a brick wall… Review the blogpost: Let the Matches Tell Us the Cluster Common Ancestor here.  TGs, just like Clusters, are groups focused on a Common Ancestor, and the Matches in a TG may be able to tell you who the Common Ancestor is.

3. When you know which line a TG is from, tell your Matches! Focus on your Matches’ Trees to find that line. With that focus, I have found a collateral line in a Match’s Tree and built it back to our Common Ancestor – many times.

4. Walk the Ancestor Back within each TG. See here.

5. Pile-on (not pile-up). In several TGs I’ve gone back to the Matches asking if they had a particular Ancestor in their Tree. Even when they had no Tree, they sometimes confirmed that Ancestor I was focused on. I’ve collected dozens of Matches who all share the same Common Ancestor with me. I’ve done this with a growing number of different TGs. This is very strong evidence that the DNA segment (represented by the TG) is from that Common Ancestor.

6. Play with these TGs. You can easily use DNA Painter to paint the TGs! All the Matches in a TG could also be painted if you want. Think about Painting virtually every one of your Matches…

7. You can easily use the G2 column to sort your TGs into a paternal side and a maternal side.

8. As mentioned before, add the data from other companies. Consolidate all your Matches and segments into one comprehensive spreadsheet.

The End of Triangulating Your Genome

I’ve enjoyed putting this blogpost together, and sharing some of my concepts on Triangulation. If you try this, please post some comments about your experience and/or any suggestions for improvement.

[10A] Segment-ology: Triangulating Your Genome; by Jim Bartlett 20201229

48 thoughts on “Triangulating Your Genome

  1. Hi Jim,
    Thanks for the blog, its an interesting variation on the Ancestry Clustering.

    The only thing I would ask is the following:
    When I am checking the triangulations for one segment on a chromosome I will often have triangulations for a subsequent chromosome. I assume you are numbering from 1 on each chromosome so we can’t use the same number but I think I will probably add a column for, let’s call them, Glocbal TG. ie. The group that covers everyone who triangulates with each other (the basis of clustering I guess). For this I won’t include siblings or children as they will link everyone together but it should speed up subsequent chromosomes because you will immediately know some people who are matches on a segment.

    I am not sure I explained that very well !

    This also looks like something that can be automated of course 🙂


    • Graham
      Thanks for your feedback – a couple of things…
      Although Clustering and Segment Triangulation both result in groups that are on one ancestral line, they are different. Clusters are based on grouping Shared Matches (with no information on segment location); and segment Triangulation is based on grouping overlapping DNA segments (with no information on the genealogy). Because our own DNA is fixed (recombination crossovers are fixed, and our Ancestors are fixed, and the segments our Ancestors pass down to us are fixed), I rely on segment Triangulation as a first choice, and use Clustering primarily at AncestryDNA (where segments are not identified). Segment Triangulation is much more precise, and each segment is taken into account – whereas each Match can only go into one Cluster, with gray boxes indicating otherwise. Also segment Triangulation at one Company, should result on the same TGs as Triangulation at any other company – Clustering can only be done within a Company, using Shared Matches. Clustering with different thresholds, usually results in different Clusters.
      Segment Triangulation is actually done within the boundaries of the 45 or 46 Chromosomes. The TGs on one Chromosome are independent – physically separated from each other. In my process you can use the characters 1 to z in each Chromosome – in the end I establish a TG numbering system which includes the Chromosome number. For example: 06G2 is a TG on Chr 06, it starts at 60-70Mbp (as noted by the G) and it’s on my paternal side (as noted by the 2). This works for the expected 300-400 TGs. However, this is my scheme – anyone is welcome to use any system they want. Another way to identify 06G2 is: Chr 06 – 67.3 to 87.4Mbp – on the Paternal side.
      Multiple Segments – when a Match shares more that one DNA segment with us, we must consider them independently. Most of the time the Common Ancestor for each segment will be the same – but not always. I have over 50 cases of Matches who share two segments – one from each of my parents. I have many Matches who share multiple Common Ancestors. I have a close cousin who shares 7 segments with me – 6 of them are from our close Ancestor, but one of them is from a distant Ancestor on another line. The outcome in one TG does not guarantee the outcome on a different Chromosome.
      Segment Triangulation is a fixed mechanical process (no genealogy needed) – there is only one configuration – I hope it will be automated someday. Most programmers, however, don’t want to stop with just the groups – they want to identify which side they are on, and that process requires genealogy and judgment. Just automating the groups would save me 120 hours of tedious work. I would welcome that.
      Hope this helps – if not, please let me know. Jim


      • I already informed Graham about the automation of the first grouping phase. The AutoSegment tool ( now has an additional excel sheet, inspired by this blog post, which automates the grouping. For MH, one then needs to manually verify each grouping, keep the group or break it into 2 groups. For GEDmatch, the groups are perfect since we already use triangulation data. For FTDNA, there is an option to employ ICW data to verify the groupings and that’s the best we can do for FTDNA since they don’t offer a triangulation feature like MyHeritage.


      • HI Jim,
        Thanks for the response. I think I didn’t explain well what I meant 🙂 … I understand the difference between Segmentation and the triangulation which you are doing …

        Actually the main thing I was really suggesting was a speed up to your process. So while checking the triangulations of a particular user, I am making a note of the ones on other chromosomes. So when I come to that chromosome I already have some matches done.

        Hopefully saves some time but maybe it would only give the impression of saving time ! 🙂




      • Graham,
        I’m not sure what “Segmentation” is. I started Triangulating DNA segments in 2012 (when FTDNA and 23andMe were the only atDNA tests offered); and I started this blog a few years later.
        I thank you for exploring different ways to speed up my manual process. I, too, tried doing the process a Match at a time (I also tried working with only the Matches who only shared one segment). No matter which way, there was a lot of back and forth. I concluded (gut feel) it was best to just walk through each Chromosome. However, it is boring; and I often deviated from that “forced march”, and went down several rabbit holes. I tried to present something that was helpful, based on my experience of actually doing it. I welcome any and all improvements that folks find. And I encourage folks to deviate from my process and document a better one. Jim


      • HI Jim,

        I meant clustering not segmentation. I mustn’t post in a rush, sorry !

        I have been gathering the triangulations for a couple of hours today to try different methods but it wasn’t helped by the MyHeritage site running slowly in showing the triangulations today. And yes, you are right, it is boring 🙂 But it is still interesting to see the triangulation groups appearing.

        I had a look at making the call direct to get the trianglations for a group of matches but didn’t have the time to give it a go.

        Thanks again for the post, it has given me a lot to think about with MyHeritage.




      • Graham – thanks for your positive attitude, and willingness to do the boring work. I think you’ll find the end result to be very beneficial.
        Two things: sometimes I jumped to one of the shorter Chromosomes – which tended (for me) to go smoother; and sometimes I just skipped over an area that was being difficult, and came back to it later.
        I hope you keep rough track of the time. Another total time will give readers another data point.


  2. Jim, in getting started with your Genome Triangulating, I wondered it you recommend including siblings? I also have a grandson on MH, but removed him from this process, because it seems to me that having him in the mix doesn’t really add any helpful info, but would add some other work to almost every chromosome. It seems to me that having the siblings, however, would be beneficial. I think the question in my mind was brought up by the Leeds clustering method, but in that case, identifying grandparents is the goal. Here, we’re to group segment matches and it seems probable that the sibling(s) matches will dominate the “long” segments, but I don’t see that as a problem.

    One general question/comment. I had to look up the definition of “avuncular,” which appears to only apply to uncles, but I’m assuming in context as you are using it, you’re intending it to apply to uncles and aunts?

    One clarification on my first comment above. When I mentioned the small matches I initially got when comparing my sisters, those were due to the setting I had on the chromosome browser. I’d been working on something else prior to looking at the sisters and had moved the browser’s “triangulated segments” setting to “2.” After moving it to 8 these ultra-small ones disappeared. Since they had all occurred at crossover points anyway, I had already assumed they were false.
    I hope I’m not being a pest with my questions and comments. Thanks so much for sharing your experiences and your encouragement.


    • Doug, I do recommend using (not including) siblings. By that I mean I have a column in the spreadsheet for siblings and children. These relatives tend to share long segments with you, which are usually on the same side. So I note the groups that include a sibling or child. When I finish forming the groups, the next step is assigning them to a side, and aligning the segments on each side so they are adjacent. If you don’t have parents tested, the siblings and children can often indicate which side a group is on.
      I meant avuncular in the sense of Aunt/Uncle/Niece/Nephew (my abbreviation is AUNN) – they, too, tend to have long, helpful, segments which span TGs.
      Our conversations may also be helping others. Jim


  3. Hi, Jim, I just found this recent blog (which I look forward to consuming) while accessing your site to share a MyHeritage experience with you and to see if you’ve tried this. I manage my two sisters’ DNA and just recently uploaded it to MH. Tonight while looking at a new match I just got a notice about, I decided to click on the trianglation symbol on the match list and see how the two of us matched with him. I don’t usually click on either sister when going through the triangulating pass here, so this was a kind of experiment. Well, we I only had 3 segments in common with this new person, and with my sister we triangulated on one of those because the sister didn’t share the other segments. Well, what happens if I through in the other sister? No triangulation! OK, what if I take the new match out of the picture? Wow, 48 triangulated segments, from 2.0 cM to 131.2 cM. There were a total of 6 < 7 cM segments and they all occurred at recombination points. I was curious if you've ever done this with siblings, or whether you have any interest in knowing more about this? One thing I can see right away is that this will be of benefit to me as I am trying to finish up my visualation process for the three of us by comparing with cousins on the paternal and maternal sides.


    • Doug,
      Although you and your siblings each got 22 full autosomes from each parent, you and your siblings got different versions of each autosome. For any particular segment, you may be the only one to get it, you and one of your siblings may get it, you and both siblings may get it, one or both of your siblings may get it, or none of you three may get it. Some of my earliest blogposts go over how each of you get segments from your grandparents.
      Yes – in my spreadsheet I have a column for siblings (I have 1), and children (I have 2 tested). They tend to share Matches (on the same side), and so they are good “tell-tales” – giving clues to adjacent TGs.
      Since you have two siblings, you should use Visual Phasing (google it) – which maps the three siblings crossover points from their grandparents. It’s a difficult process, but then you have your grandparent crossover points mapped. And, YES!, you’ll see these same Crossover points between TGs. There should be about 37 of them (give or take a few) for each side (maternal and paternal). They separated your grandparents’ DNA segment in your DNA. Your DNA also includes about 37 *more* Crossover points from your Great grandparents; and 37 more from each generation going back. And your set of Crossover points is fairly unique, although some of them will be shared with one or both siblings. They are unique, and fixed (they don’t move or change in your DNA) – that’s why I like segment Triangulation – it identifies these Crossover points. They separate the TGs. Jim


      • Thanks for your response, Jim. Yes, I’m aware of the visualization process and have been through Blaine’s series a couple of times and have also tried working with the Fox visualization Excel tool. I have been working on these over the last few months. I’m pretty much completed with the identifying of the recombination / crossover points but still having some problems identifying the correct grandparent on some of the chromosomes. That’s what excited me about looking at the three of us with the MH chromosome browser and then adding in some of the cousins (one at a time) to help verify which grandparent is which on some of these segments. But, we’ll get there. I just want to say how much I’ve learned from and appreciate your writings. Thanks and keep at it.


      • Doug, Thanks for the kind comments. Segment Triangulation using a 10cM threshold should result in 300-400 Triangulated Groups – each one representing a segment of your DNA. Your 4 grandparents provided about 118 segments; your 1G grandparents about 192; 2G grandparents 266 and 3G grandparents 340 segments – so the 300-400 TGs would average out at about 3xG grandparents. Of course at that distance the DNA gets more and more random, and Matches with smaller shared segments within a TG will often go back more generations. Figuring out the crossover’s from your grandparents is a great start!



  4. Your match list shows more than 14 thousand matches yet your numbering system of single digits and alphabet letters totals only 36 possibilities. I started with the first name on the list of matches (number one) and am just numbering them consecutively as I work my way down the list. I’ll end up with numbers in the thousands. I What am I missing?


    • Julian, I need to be more clear on two points:
      1. Yes, the first Match-segment gets a 1; then, using that Match as a base, check for all the Match-segments which Triangulate with that base, and enter a 1 for them too – this way you form a group all of which have a 1. Any Match-segment which Triangulates with those, also gets a 1. The “1” group is a Triangulated Group (each of the Matches in that group should match many (but maybe not all) of the other Matches in group 1.
      2. When you start with Chr 2, begin with 1 again. You should be able to identify all the the TGs in each Chromosome with a single character, 1-z.
      In the end, the TG ID will be a combination of the Chr # and a letter, and each TG should then have a unique ID.

      Hope this helps, Jim


  5. Hello again, Jim,

    You will be happy to know that my Chromosome 13 mystery with the 30 cM segment located within the 51 cM segment is solved — I think. I went back and took a really hard look at the 55 matches within my confusing Mr Arizona TG. Once again I found that these 55 matches were not matching the 46 people in the California Girl TG even though they were in the same segment range.

    But, I noted a few new things. I had tentatively previously marked one of the Arizona group members as a possible early Wessling family member, a group which had its origins in NW Germany. About 3 of the Arizona group people had matches with a known member of my Wessling group (but not an Arizona group member). Now, it gets better. Some 23 matches of the Arizona group live in Germany or the Netherlands or Sweden, so this fact was telling. My mother’s people have been in the US since the 1600s and before that most of them were British. On the other hand, my dad had this one key group of ancestors from NW Germany.

    I had absolutely discounted the possibility of this Arizona TG being on my dad’s side because so few (less than 10%) of my matches have been on that side. But, this seems to be a case where some of those NW Germans have passed their DNA down via Chromosome 13 to my Arizona group members. This solution also totally accounts for the fact that the Arizona people are not matching the California Girl people. They wouldn’t be expected to match because they are each getting Chromosome 13 data from different halves of the total chromosome. And, of course, it solves the problem of why didn’t any of those people who seemed to share the same segment were not matching.

    Once again, thanks for helping me solve this problem.


    • James, The insight here is to follow the data! Triangulation is a fairly rigorous process that should result in a firm grouping. Conflicts are almost always caused by having the wrong Common Ancestor. When I started with Triangulation, I had a 2C with 7 shared segments, and I used the same CA (our common Great grandparents). But for one segment there was a clear conflict. When I really dug into the 2C’s Tree, I found we were also 5C on the other side. The CA on that side did fit in the TG.
      On the positive side, as you determine the parent and grandparent for each TG, those TGs become pointers to the part of your Tree to look for more distant CAs…. This is why I refer to TGs and a Chromosome Map as valuable, powerful tools for your use. Jim


  6. Hello Jim, and a Happy New Year! Thanks for all your good genealogy work. I have been giving your My Heritage strategy a go, starting with Chromosome 13. For me, this was a modest sized group with 142 matches there — and it is a group where I have a good amount of data on some of those matches. In doing this effort, I have already run across some questions that may also be common to others.

    As a little background, I have 9,000 My Heritage matches. My father’s people came to the US from Germany in the 1850s while my mother’s people have been in the US since the 1600s, so I am getting well over 90% of my matches from my mother’s people. Further, I am generally familiar with my father’s matches — they have higher scores and are usually some degree of 2nd cousins. So, phasing is not usually a problem. My experience on Ancestry, FTDNA, 23 and Me, and GEDMATCH all tell me that my father’s people are only 5-6% of my total matches.

    For my 142 matches in Chromosome 13, I have divided them into 7 well-clustered groups as we move through the segments from smallest to highest numbers. Four of these groups are quite small, with only 3-4 people each. My largest group has about 50 matches. One of these matches, California Girl, had a cM segment of 51 in this chromosome, so I used her as the key person in that group. She is a 3rd C 2R, descending from my GGF, so her score is much higher than one would expect. She and I have over 100 shared matches, and for C#13 I identified about 50 of them whose scores fall neatly in her same range, who all score over 10 cM on C#13. California Girl has a start at 27,399,818 and a stop at 73,065,967. I feel good about this group of matches.

    However, within that same range there is another well-defined group with 50 matches. This group’s key man, Mr. Arizona, has a 30 cM segment going from 31,273,632 to 59,121,802, and there are about 50 people in that group who match with him. Yes, those numbers are right. California Girl’s score start earlier than Mr Arizona and end after his stop number. Yet, Mr Arizona and California Girl do not have a shared match with each other, and the matches within each of the two groups are also distinct from one another. It would have seemed that Mr Arizona and all of his matching people should have been shared matches for the California Girl people but it isn’t happening that way. Now, if it means anything, the very first lower scoring matches of the California Girl group, about 30 matches, are almost all shown to be shared matches with California Girl and are included in that group — but as the numbers of the start area get higher (but still within the range), more matches slide over to the Mr Arizona group side. I don’t think phasing is the problem, because I would have been aware of it if these people were on my father’s side — and further, none of them are showing shared matches with my higher scoring father-side people. So, my basic question is: “Why are there two distinctive groups within this same scoring range?”

    I have another question which should be easier to answer. I have some good genealogy data on some of the California Girl matches. I know that she descends from my GGF. I also know that another member of that group descends from the father of my GGF. Does that mean that this entire group of matches is getting their DNA for that family branch as shown on C 13 from my GGGF — or perhaps an even earlier person. In other words, both California Girl and others in the group should be getting their C13 segment from the same source, however many generations back that may be.

    Hope you can help.


    • James,

      You work your way down a Chromosome, and group Match-segments as you go. You point out a lot match with California Girl. Select a new base Match near the end of that group and see who else TGs with this new base – often a TG is entended (made longer that way. This may or may not include Mr. Arizona. If California Girl’s matches match Mr. Arizona, then you have one TG; if not, you have two TGs. It is possible for the first segment in a TG to not Triangulate with the last segment in the TG – it’s OK.
      Each TG represents DNA that came down to one of your parents to you. Alternatively that segment is from a parent and a grandparent and a GGGP, etc. So, yes, the ancestral line for each TG may extend 5 to 10 or more generations back. Somewhere, you “run out of” genealogy and cannot find another Common Ancestor going back…. Jim


      • Jim, Thank you for your quick response. I’m still a bit confused at the results I found. I would have thought that when one of my matches had a 31 cM segment on a certain chromosome within the segment range of another match who had a larger 51 cM segment that the 31 point segment should be identical and that the two of them should match — but they don’t. And it happens that way sometimes.

        One thing I have learned is that to establish a solid TG you not only need to identify a common segment area on a specific chromosome but that the matches within the TG need to be shared matches. That is, you can have two matches who share a given segment but those two people will not necessarily be shared matches and thus are likely to be in different TGs.


      • James,

        You’ve hit on the crux of the issue with Triangulation – landing on the right chromosome. A 31cM segment totally within a 51cM segment, must either Triangulate with the 51cM segment or be in a TG on the other chromosome from the 51cM segment – the 31cM segment is too large to be false. Look for other, smaller segments that TG with 51cM segment or the 31cM segment – they may for two different TGs – on opposite sides (one paternal, one maternal). In a few cases, I’ve seen the smaller segments “stitch together” the two larger segments. This means the one or both of the larger segments isn’t really the full segment it appears to be – it’s been made larger by imputed SNPs which are not considered in TGs. … Jim


  7. This has inspired me to have a go at creating TGs from my own data. I have a DNAGedcom download of triangulations at MyHeritage, which makes it easy to automate the process. To acquire the download required running the DNAGedcom client for several weeks last summer, so it is not necessarily quicker than your method but a lot less work. The basic algorithm is:
    1. Select a segment
    2. Find all the segments it triangulates with
    3. Find all the segments they triangulate with
    4. Repeat (3) until no more segments can be added and the TG is complete
    5. Repeat (1)-(4) with another segment until no segments with triangulations remain.
    It took me a few hours to code yesterday afternoon, but I now have 203 TGs based on segments over 10 cM, or 375 based on all segments. There are numerous places with more than two TGs, which I have yet to investigate properly, but this accords with the little bit of manual analysis I have done which found more than two TGs in some places using MyHeritage’s triangulation. Now to work out which ancestors they are associated with…


    • Actually my process (or algorithm) is a little more efficient in that it eliminated step 3 – there is no need to determine all the pair-wise Triangulations. Once a TG is formed with two segments (plus your own), all you have to do is add segments which Triangulate with one other segment (in addition to your own). I often do this twice, just as a Quality-Control check, and to avoid errors. But not for each pair – which, in fact, won’t work in many TGs: the segments on one end (of the TG) may not overlap the segments on the other end enough for a match.
      Based on the 7cM threshold I used over the past 8 years, I have 372 TGs – so it appears from that metric, you are definitely on the right track.
      One word of caution. It is important to Triangulate *segments*. Many of the processes I’ve seen Triangulate *Matches*. Triangulating Matches works when those Matches share only one segment with you and the other Matches. When they share multiple segments, a faulty “Triangulation” can occur (not based on overlapping segments). I’ve used DNAGedcom for years – it is a great program for downloading data and for Clustering (which is not the same as Triangulation). Triangulation of shared DNA segments treats each segment separately. This is important for endogamy. Clustering does not handle endogamy well, because it does not handle multiple segments well.
      I’d be interested in your observations of multiple TGs. My experience is that these occur because of close relatives (parents, children, siblings, avuncular, 1C and 2C) who tend to share DNA larger segments that span TGs. In an automated process, this can be fixed by making one pass without those large segments to get the TGs set; and then making another pass to add them back in (these long segments really need to be indicated in each of the multiple TGs they Triangulate – same problem with multiple segments in Clustering). These close relatives/large segments are very valuable in assigning “sides”, so they need to eventually be included. All of this is why, so far, I prefer manual Triangulation. But any process that automates the bulk of Triangulation would sure avoid a lot of the tedium of my process. I did a comparison of using both processes (Triangulation and Clustering) on all of my FTDNA Matches/segments>7cM. The results were VERY close. When I manually reviewed the multiple-segments issues, I got very close to 100% alignment. Meaning that both processes point to a unique Common Ancestor – a very important and valuable outcome. I used Clustering extensively at AncestryDNA, because they did not provide segment data; but for the other companies (with segment data), I prefer Triangulation because it is more precise and uses all the DNA data (and it provides a map of my Genome which lets me add new Match-segments easily). For me, the end game is finding the most distant Ancestor I can for each segment (TG) of my DNA.


      • Determining all the pairwise triangulations is no work, it’s what the download gives me. Step 3 is necessary or you only have the triangulations with one segment, and may only get one end of the TG as you describe. You need to keep expanding the TG by finding every segment that triangulates with any segment already in the TG, and repeating that until there are no more to find.

        My multiple TGs can’t be due to close relatives as my top match is a 4C1R at 82 cM. I suspect it is due to the issue you mention in your post of imputed SNPs being used for matching but not triangulation.


      • My point is that my process addresses every segment – each one pairs with others, or it is false (actually a segment over 15cM may be the only segment for that particular area of a Chromosome). If every segment is analyzed, that’s all you need. Once a segment is grouped in a TG, it does not need to be revisited. A segment at the other end of a TG may well match previously triangulated segments, but those previously triangulated segments don’t have to be used as a base segment. But this discussion is mute, if all the Triangulations are automated. It just doubles the work (A to B *and* B to A), but what’s a few minutes to a program.


      • I thought my process was clear on this, but maybe not. Pick a segment as the base; annotate all the segments that Triangulate with it; then pick the next un-annotated segment as the new base; and repeat. In this way you “touch” every segment – each segment is either a base segment or a segment which Triangulates with a base segment – all are Triangulated, except a few that don’t Triangulate with any others. If these overlap a TG on either side but don’t Triangulate, they are probably false; if they stand alone, they may be the only segment in a given space on a Chromosome = wait for more info.


  8. Hi Jim,
    Excellent article as always.
    Are you keeping a separate spreadsheet for each testing company?
    How will you deal with new matches as they accumulate at each company?


    • I have only one set of DNA – the data has to conform to me, no matter which company it comes from. My crossover points, and thus the TG segments are fixed. So I put all the segments in one spreadsheet.
      As I get new segments, I tag them with today’s date, add them in, anywhere, and then re-sort the whole spreadsheet by Chr + Start. I then just search the spreadsheet for today’s date and adjudicate each one – does it Triangulate with a Match on one side or the other. Just to be sure, I usually triangulated with two Matches.
      The hard part is determining which are the new Matches. It’s easy at GEDmatch and FTDNA. For the others you could ask Genetic affairs to tell you the new ones. Another way (fairly complex) is to compare your current spreadsheet with a new down load and use the ones that don’t match up. Jim


  9. This is a different spreadsheet than the one you used for 23 and Me. I was about to begin working on triangulating and grouping my 23 and Me results. For someone like me who is just getting into segmentology (I’m reading all your posts which I find to be excellent) would it be best to use this method and spreadsheet for any triangulation grouping of tests from the different companies I’ve tested at? Thank you so much much for all your posts. You are a true asset to the genetic genealogy community.


    • Bob, Thanks for the kind feedback. Any spreadsheet will do – Just download your segments at 23andMe and use that spreadsheet. Add columns when you need them. Review the blogpost and the figures to see the ones I recommend. The order doesn’t make any difference – in fact, I sometimes move some the columns around. For grouping, the one you’ll use the most is one for the ID# – that column is the key. I’d do one company at a time…


      • I’m 1b, too. I do leave the house four times a day … to walk the dogs. If I walk them a mile, they will take a nap and I can get back to genealogy until time for their next walk! I’m definitely a spreadsheet person, so this is right up my alley. I just finished grouping the segments on Chr 20. Guess I’ll try a little bigger chr next. Your instructions are so specific and easy to follow. Thank you for all you do for the genetic genealogy community and for sharing with us.

        Liked by 1 person

  10. Jim,

    I love your postings and have found them extremely useful. Especially your thoughts on the smaller segments. I admit I haven’t thoroughly read this posting on your process, but are the results much different than what you would get using Genome Mate Pro?

    I’ve used GMP for a number of years and love how it organizes all my data. However, I rarely find it recommended. Sorry if I’ve stumbled onto some turf battle or something. That’s why I chose to email you rather than make a comment on your blog.

    Thanks for your willingness to share so much of your thinking and process.

    Jennifer Clark Sent from my iPad



    • Jennifer, Thanks for your feedback. I recommend all the tools – whatever works. Each person has their own favorites. I was several years into my Excel spreadsheet when GMP came out. I tried it, and it was good. But the thing is, I didn’t want to abandon my spreadsheet and start on a different platform. I was the same way with Clustering – all three programs work, and I just settled into one of them for most of my Clustering work. With all the data that is still pouring in, it’s difficult to keep up. I’ve stopped tracking most segments under 10cM. There is good information in some of the small segments, but I’m pretty much done with gathering and analyzing segments – my segment map is done, and my focus now is on digging out Common Ancestors.
      With GMP have you determined 300-400 TGs – all adjacent to each other, and covering all of your 46 Chromosomes? If so, then GMP should be recommended more. If not, then I would recommend my process in the blog post. Within a finite amount of work time, you can determine how virtually all of your DNA breaks down into segments from Ancestors. What’s left is determining the correct Ancestor for each TG segment.


      • Jim, I work primarily with my mother’s DNA test. Using GMP I have been able to map her paternal side with about that equivalent number of TGs. Her maternal grandparents were recent immigrants from an area of Germany where few people have DNA tested or where few people migrated to other continents – so finding any match is pretty difficult.

        What I like about GMP is one database includes tests for my brother, a maternal cousin, and myself, and that helps me to at least be able to determine which side a TG belongs to.

        I started with GMP very early on in my DNA work, so, like you, I’ve stuck with what I’m familiar with.

        I do have a number of TGs that I haven’t found an ancestor for – but that’s because the groups all point to colonial New England. Either I can’t work a match’s tree back that far, or there are several possible shared ancestors.


      • Jennifer, I cam empathize – my maternal grandmother’s father was an immigrant from Scotland (CAMPBELL) and her mother was an immigrant from Germany (WEHRLE). I have only a handfull of cousins from this lines, and a number of TGs with no known Common Ancestors, and aa few TGS which are blank (no matches with that segment).
        I have spreadsheets for my brother, uncle and father – sometimes I’ll combine then all into one and compare information. But I always separate them apart again – the segments are not compatible! As I pointed out in the blogpost, I have columns to indicate when one of my Matches also match a child, sibling, parent or close cousin. These close relatives tend to share large segments of DNA with me which may include several TGs. They often help in linking TGs end-to-end.
        In the end, it’s the quest for Common Ancestors with Matches that is the key (mapping the segments is done). I’ve long since documented all of the obvious CAs. I’m now using the Groups to help me find more – often I need to extend a Match’s Tree to find the CA.


    • Jennifer, You may already be there, but MyHeritage has more European DNA testers – I have 124 matches in Germany and 84 in Switzerland. I wish there were more.


      • Yes, I do have my tests at MyHeritage. And that site has been somewhat useful for my Pommern ancestors. A lot of folks from there also migrated so I can find their descendants at other sites. Fortunately, I’ve been able to document my Wuerttemberg ancestors through church records, many lines to the late 1500s. They are the group with few DNA matches.

        Back to MyHeritage – their marketing must be paying off – most of my good matches for all branches of my tree over the last 6 months have been there.


  11. Hi Jim,
    Extremely nice roadmap – just WOW. I’m still working on clusters and collecting segment data for known ancestor matches using Excel. Haven’t started inputting DNAPainter.

    120 hours? And on the 6th day you rested?

    Liked by 1 person

    • Randy, On the about the 50th day… I had a libation and started collecting my notes to write the blogpost;>j I’m a big fan of Clusters – particularly for Ancestry data where there are no segments. But I’m convinced the “end game” has to be linking Ancestors to Segments – it’s the only way to smoke out the NPEs. Also, to some extent, TGs really help with endogamy, because each segment (TG) stands on its own merit – it comes from one path down to me. It’s still a hard puzzle to solve, but a lot of Matches in a TG all on the same path (somewhere), sure helps.
      About a year ago, I inputted my 372 TGs into DNA Painter. It gave me a nice picture of what the DNA said, but it’s just that – a different picture of the same thing. The chromosome painting is the same data as the TG segments – just a different way to view it. For me, it’s easier to work with (sort, compare, manipulate) the spreadsheet. Others get a lot more out of the visual picture.


      • No genealogy for me from Mar-Nov – demands of the hobby farm, but it’s good. Maybe by the time I get back to to the mega match project, someone will have written software to automate the process. Happy New Year! – hope 2021 is your best year yet.


  12. Hi Jim, very interesting blog post. I am not a segment expert but it seems this process is more or less an offline DNA painter profile using Excel? Some thoughts. Are you correcting the basepair positions for FTDNA segments, since they are based on build 36? I have shared segments with the same match on FTDNA and MyHeritage and some segments are not overlapping. Also, it seems like a large portion of this work can be automated? As you perhaps know, I’ve tried that as well and came up with AutoSegment: Doesn’t make the comprehensive spreadsheet, but instead create segment clusters, probably similar to your TGs. It’s also possible to combine the four sites that provide segment data, and to make data more comparable I perform a liftover for FTDNA.

    I am currently finishing up a version for FTDNA that is using ICW data to verify overlapping segments. Segments that overlap, but whose matches are not shared matches, are not valid and won’t make it in the same segment cluster.

    Liked by 1 person

    • EJ – Thanks for your comments. I am a long time fan of your work. As you can tell from my post, my focus is on the whole genome. I’ve been a genealogist for over 45 years, and have gone about as far as a can with paper research. When atDNA came along in 2010, I used it to find Common Ancestors for a few years, and then got hooked on segments and the bigger picture. Mindful of brick walls and NPEs, I am focused on linking my DNA segments to my deepest Ancestors. I want the full map, and I want to build it up a generation at a time.
      This is an offline process, with Excel, I’ve been developing and using since 2012. I have not corrected FTDNA segments. I have all my FTDNA, 23andMe, GEDmatch and (most of) MyHeritage shared segments in a one spreadsheet (over 20 thousand rows). My 372 Triangulated Groups are heal-and-toe from beginning to end of each Chromosome, with only 10 or so, small gaps. The ends of these TGs are often a little ragged – FTDNA using different build; MyHeritage inputations; etc. But my thesis is that my crossover points are fixed, and almost all shared segments will fit within them – with fuzzy ends. I’ve mapped my DNA segments – I now want to verify where they came from (and thus verify the genealogy). I think TGs and Clustering are great tools for this objective.
      Some have tried to automate this process. GEDmatch did a pretty good job; and MyHeritage and 23andMe have very accurate TG indicators – unfortunately there is still the issue of mapping all this data. As with Clusters, multiple shared segments must be dealt with. And there will always be the issue of a Match who shares multiple Common Ancestors with me. It always comes back to which Ancestors go with which segments.
      I tried to help FTDNA several years ago – they tried, but never got the brass ring. I believe overlapping FTDNA Segments PLUS being on the ICW list with each other makes a solid TG. I Clustered ALL of my FTDNA Matches (7cM threshold), and found an almost 1 to 1 correlation with my 372 TGs (after I analyzed the the multiple segments independently and made some adjustments in Clusters) This convinced me that both TGs and Clusters are focused on a Common Ancestor.
      I think one of the important outcomes of Clustering (and TGs) is the identification/elimination of false segments.

      Liked by 1 person

      • Hi Jim, thanks for the elaborate reply. Glad to read that you also found that ICW data can serve as evidence for overlapping. I think that’s the best you can do with FTDNA, similar to their matrix system. I still think there is some added value supplying the corrected FTDNA values since for some chromosomes a 10 cM segment for FTDNA wasn’t overlapping with the same 10 cM segment on MyHeritage. That will be impossible to place underneath each other unless you correct for it. I think my AutoSegment tool would be an excellent candidate for your Excel file. All the necessary data is there, (corrected) segment data, overlap, etc etc. The only thing different is the overlap calculation, I don’t use Mbps but instead, calculate the overlap in cM using genetic maps. Doesn’t really matter too much, but in some cases, there is quite some difference. In that case, the TGs are probably not separate but should be combined to reflect the underlying recombination characteristics. Let me finish my new tool in the upcoming days, I’ll spend some time seeing if I can replicate your Excel file automatically.


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