A Segment-ology TIDBIT

A question recently came up: Are the Ancestors on two sides of a crossover point, always a mother and father (in either order)? Or: If I know the Common Ancestor (i.e. the father or the mother of the TG couple) of a TG segment, must the next TG segment be the other parent of the TG couple.? The answer is YES, with an important caveat: only when we are talking about mother and father of our Ancestor who created the crossover.

Important scientific fact: A crossover is formed when a human recombines two Chromosomes to create a new Chromosome that is then passed to a child. One of the two Chromosomes is from the Mother, and the other is from the Father. So one parent is on one side of each crossover, and the other parent is on the other side of the crossover.   Here is Figure 6 from my 2015 blogpost: Segments – Bottom Up:

Note: each of the Chr 05 lines above is your Maternal Chr 05 – it’s just broken down for each generation. In the Grandparent look, the two crossovers were created by the parent using grandparent segments (assuming an average of 2 crossovers per generation for Chr 05). Note the Ahnentafel numbers to represent generic ancestors – even numbers are males, odd numbers are females. The first crossover created by the parent shows 7 & 6, or female & male, on the two sides of the crossover. When the first grandparent segment ends at the crossover, the next segment is the opposite parent. The second crossover created by the parent has 6 & 7 (male & female) on the two sides of the crossover.

The next line – the Great grandparent look has 2 more crossovers – created by the grandparents, when each of them recombined their respective 2 Great grandparent chromosomes. One of the crossovers is between 14 & 15 and the other between 13 & 12 (there was no crossover when the Ancestor 14 segment was passed to daughter 7). So again, each new crossover has a male and a female (in some order) on the two sides of each crossover.

Check out the two crossovers (on average) added at each of the next two generations – they all have the mother on one side and the father on the other side of the crossover.  Note carefully the word “added” (or created or formed).

Now here is the catch… In the Great grandparent look above, the last crossover has 12 & 14 on each side – two males. This seems to contradict the basic concept. And if we were applying the basic concept to TGs at the Great grandparent level it would be wrong. What’s up? Well, what looks like a crossover between Ancestors 12 & 14 is in fact a crossover – but it was formed by Ancestor 3 when she recombined Chr 06s from her parents 6 and 7 – these are the two parents of the ancestor who first formed (or added or created) the crossover.

When we form Triangulated Groups (TGs), we use groups of overlapping segments. But there is nothing in the TG criteria about the generation of the TG. We do understand that the TGs start and end at crossover points – when we shift from one Ancestor’s DNA to another Ancestor’s DNA. But until we can Walk the Segments Back (generation by generation), we don’t know when the crossovers were formed. There is one generation for each crossover, but until we have Chromosome Mapping we don’t know which generation it is.

Note: A TG Summary Spreadsheet will give good clues to the formation of crossover points – see Observation 5 (see linked blogpost).  In generation after generation the older crossovers can be seen, with only about 2 new crossovers in each generation. So the farther back we go with Chromosome Mapping, the newly formed crossovers will be there (with mother and father on the two sides). But the other crossovers may not appear to be mother/father, unless the origin of the crossover can be determined.

Bottom Line: With TG segments, sometimes the next TG on a chromosome will be the other parent, but more often it will not.

Edit 20240403: It was suggested that I add a Chromosome Map, showing segments from my 16 2xG grandparents. Here is one I did in 2013:

[22CA] Segment-ology: What is the Next Segment? TIDBIT by Jim Bartlett 20231209

A Segment-ology TIDBIT

I was adjudicating a ThruLines from a Common Ancestor (CA) down to a Match. The grandchild of the CA didn’t fit. I find about 5% of my ThruLines are wrong so I just dotted the Match yellow (TL Wrong) to add it to that group. But as I was about to close out the Match, I clicked on Shared Matches (which I usually do anyway). The Match was at 13cM so I didn’t expect much. Surprise – over 20 Shared Matches, and almost every one was confirmed or “likely” to be on the line indicated by ThruLines! A clear consensus. I went back to the Match’s line and found another path that worked – back another generation from the ThruLines CA hint!!

The details don’t matter. The moral of this story is that a ThruLines CA AND a consensus of Shared Matches AND the AncestryDNA “side” should all be in agreement. This applies to CAs at other companies, too – the clues should be in agreement.

Takeaways:

1. When you find a CA, be sure to also review the Shared Matches and the side.

2. When you are searching for a CA with a Match, review the Shared Matches first to see if there is a consensus clue.

PS: this assumes you have diligently done your homework and put all known or likely CAs in the appropriate Notes (same for every company).

[22BZ] Segment-ology: Census TIDBIT by Jim Bartlett 20231206

BLUF: 1. Focus on lower cM Matches in a Cluster to determine the Common Ancestor; 2. Reduce the Cluster upper limit to cull out closer Matches once their ancestral line is imputed to more distant Matches. Known Matches impute to unknown Matches who carry the ancestral line to the next group of Clusters which split only to the parental Ancestors of the previous Matches. Unknown Clusters may well be Bio-Ancestors.

In case you missed one of my many blogposts on Clusters: Clusters form on Ancestors!

This comes from two “facts”: 1. Each of our DNA Matches shares at least one segment of DNA with us that came from a Common Ancestor (CA) – the basic tenant of genealogy DNA testing – the caveat being the segment needs to be Identical By Descent (IBD); i.e. a true segment; and 2. Matches who share the same CA will tend to show up on each other’s Shared Match lists. The inverse is that when a group of Matches show up on each other’s Shared Match lists (i.e. each of your SM lists with them include many of the same Matches), they will almost always share the same CA.

“Clusters form on Ancestors” is a powerful observation – when it happens… And beware the Cinderella slipper – don’t try to force fit a Match into a Cluster if they only share with one or two other Matches – easily seen in SM lists and on the fringes of some Cluster diagrams.

So let’s dive a little deeper. A lot depends on the mix of Matches that are being Clustered. In a perfect world we’d like to Cluster, say, only 3rd cousins (3C) – the resulting 8 Clusters (hopefully) would be 1 Cluster for each Great grandparent. The average for a 3C is 73cM, but a true 3C can range from 7cM to 234cM (per the Shared cM Project 4.0). The point is there is NO cM range that would only include 3C. And it only gets worse with 4C and beyond (and if you follow me – I go way beyond 4C). So: Live with it! We can take some measures to tighten up our Clusters as we Walk The Clusters Back (WTCB).

When we start with an 80 or 90cM lower threshold for a Cluster run, we usually get 4 Clusters, with one for each grandparent. These Clusters tend to follow the rule. But beyond that, with smaller cMs and more distant cousin-Matches, the randomness of atDNA comes into play. We can say the growing numbers of Clusters (as we lower the cM threshold) will tend* to a CA. But I use “tend” because it’s not a guarantee – it cannot be a rock solid rule – “the random DNA didn’t get the memo”.

So, can we have a Cluster using a Cluster run of 60-300cM have 2C, 2C1R, 3C, 3C1R, and 4C Matches in it? Absolutely! They should all be on the same line, but that brings up two important points.

1. Old saying: “Everybody has to be someplace”. The 60-300cM range covers all those cousinships (and more); and in Clustering, every Match “has to be someplace” – it will go into some Cluster! Some of the higher cM Matches (closer cousins) may well have gray-cell links to other Clusters. The way I think about it is that they are “confused” about which Cluster to be in – they are tugged in several directions – but the Cluster algorithm always picks one Cluster. My advice for these Clusters is to focus on the CAs of the smallest cM Matches in each Cluster – usually the most distant Matches – to determine the CA of the Cluster. Hopefully we’ll get a clear consensus (but remember Cinderella’s slipper).  The higher cM Matches in each Cluster often will have gray-cell links to other Clusters – this serves as a QC (Quality Control) check that the several Cluster CAs are related and appropriate. It also confirms these higher cM Matches are closer cousins, descending from all the CAs of gray-cell-linked Clusters.

2. It will also help to reduce the upper cM limit, to cull out some (but probably not all) of the closer cousins as the lower threshold is reduced in the WTCB process. These “closer cousins” have already “done their job” for WTCB. They have helped determine Matches who are one more generation back. In other words, your 2C Matches will help identify your 3C Matches (who have to be from one or the other of the 2C parents). At each Cluster run this information is imputed to the other Matches in their respective Clusters. This is not perfect – there will also be some 2C1R, 3C1R, half 3C, 4C1R in the mix. But it gives you a much better/tighter picture of the CA of each Cluster. These imputed/”tagged” 3C Matches will carry the ancestral thread to the next round of Clusters. Remember, going back in generations, there are only 2 possibilities in the next generation – the father or the mother. Reducing the upper cM threshold will cull out Matches that have already “passed on” their Ancestral line, and will force each new Cluster to group on itself.

The point is to make successive Cluster runs, lowering the thresholds each time to get more Matches, who tend to be a little more distantly related and will divide up into new Clusters which will be a little more distant. In each of these new Clusters there should be a mix of “old” Matches (from previous Clusters, some with known relationships, and some with imputed CAs), and “new” Matches (some with known relationships and CAs, and some unknowns which will be imputed based on analysis of all the Matches in the new Cluster).  

Note 1: Usually, I use CA to note the Common Ancestral Couple between myself and a Match. Clusters tend to form on specific Ancestors. Are they individual Ancestors or the parental couple? I’m not real sure. I will say that I rarely find a Cluster that I can identify solely to a female Ancestor. This makes sense because most of the time the husband/wife couple are together. So I will continue to use the male Ahnentafel number to describe my Cluster CAs.

Note 2: WTCB is a relatively easy process to start, but with each iteration it gets harder – both because of the approximate doubling of Matches at each step but also the inevitably difficult Cluster(s) to sort out (probably a brick wall). In any case you can start manually by just walking down your list of Matches in cM order and coding them (I’d use the Ahnentafel Number) and checking with their respective Shared Match lists. Stop whenever you want. (For me, the first two WTCB iterations were easy (a few hours); and then I worked on one a day for several more…. Your results will vary, depending partly on the amount of “Notes homework” you’ve already done.

Note 3: This is a great tool for bio-Ancestors, Brick Walls, NPEs, etc. Using this WTCB process will identify known Clusters. Some may leave you stumped (a few did for me). One reason you may be stumped is because you have no known/imputed Matches for a new Cluster – just Matches staring back at you with no clue how you are related. The WTCB Cluster comes to a halt. Now’s the time to examine all of the available Trees from the Cluster. If the Cluster Matches have their own CA, you have a BINGO! That’s probably your Ancestor, too. Check any gray-cell links to other Clusters to learn more about where in your Tree this could fit.

[19O] Segment-ology: WTCB Observations and Advice by Jim Bartlett 20231130

A Segment-ology TIDBIT

Bottom line up front: Triangulation and Clustering should have pretty much the same result at each company. This may allow imputing some Common Ancestors from Ancestry Clusters to the other companies and imputing some Triangulation segments from other companies to Ancestry Matches.

It may seem obvious, but it bears repeating. Your ancestry is fixed, static, unchanging. Your biological ancestors are determined at conception and cannot change. Your parents, grandparents, great grandparents, etc. remain the same no matter where you test.  Likewise, your DNA segments from Ancestors are determined at conception. These segments do not change throughout your life and are the same no matter where you test.

Therefore, the grouping methods we use should be roughly the same no matter where you test.

Your DNA segments don’t change. Segment Triangulation is based on your DNA segments. Each Triangulated Group (TG) is based on one of your DNA segments. A TG formed at any company would be the same specific segment at each of the other companies. In fact my DNA segment spreadsheet has 372 TGs formed from segments from all of the testing companies. The segments identified by each company “fit” into my TGs. There might be very slight differences among the companies, but the overall segments still fit only one way.

Your Ancestors don’t change. Take, for instance, the LEEDs method, which groups your 90-300cM Matches into four groups – one group for each of your four grandparents. No matter where you test, the four groups would be the same – one  for each of your four grandparents.

LEEDs is a special subset of Clustering. Clustering groups Matches on your Ancestors. Clusters should form on the same Ancestors, no matter which company is being used (Clustering depends on Shared Matches aka In Common With or Relatives in Common). It’s almost like a parallel universe at each company – for a given range of Match cMs, about the same Ancestor Clusters should result – based on your Ancestors. Clearly a Match who has tested at two or more companies, should show up in the same Cluster at each company. Maybe not 100 percent of the time, due to the vagaries of Shared Matching, but most of the time.

I need to try Walking The Clusters Back at each of the companies (at various cM thresholds) and see how parallel they are. I strongly suspect very strong concurrence with the larger Clusters, and large cM thresholds. Perhaps at some point, with lower cMs, the concurrence will drift away .To be continued…

Takeaway. We can Triangulate segments at 23andMe, FTDNA, and MyHeritage – giving each Match a TG for each shared segment. We can Cluster Matches at 23andme, FTDNA and MyHeritage, and note any concurrence of TG segments in these Clusters (usually one or a very few). We can determine some Common Ancestors at these companies. We can determine many more Common Ancestors at Ancestry (particularly out to 6C with ThruLines). We can Cluster at Ancestry and note any concurrence of Ancestors in these Clusters (there usually is one). Some Ancestry Matches have also tested/uploaded elsewhere, so we can determine their TGs. We can then compare Ancestry Clusters with Clusters at the other companies for congruence – allowing us to impute Common Ancestors to the Matches at other companies, and TG segments to Ancestry Matches. Maybe not in all cases, but probably in some cases.

[22BY] Segment-ology: Triangulation and Clustering Among Companies TIDBIT by Jim Bartlett 20231028

The segment Triangulation Mantra is: 3 separated cousins match each other on the same DNA segment – don’t use close relatives or segments below 7cM.

Besides the fact that this Mantra works, let’s back up a little bit and review why it works – what are we really trying to do. Well… we are really trying to insure all the segments in a Triangulation are from the same side – from just one of your parents. We have two of each chromosome – one from our mother and one from our father. We want our segment Triangulated Groups (TGs) to be on one just one of these chromosomes – to insure we are looking for a Common Ancestor on one side of our Tree (and to insure we don’t intermix the data from our two chromosomes to create a false segment in our TG).

What we want are shared DNA segments on only one of our chromosomes! On one side!

So…. What if we know some of our Matches are on one side – each one is definitely on our maternal or paternal side?  Our segment Triangulation becomes almost trivial. Overlapping segments on the same side are Triangulated.

If we have DNA tested a parent, we can relatively easily determine which Matches are on that side. For these, all that is required is segment overlap for Triangulation.

If our parents have significantly different ethnicities, we can often separate many Matches into maternal and paternal sides. Segment overlap with either side equals Triangulation.

Shared Matching (ICW) groups which are clearly one side or the other allow Triangulation just by overlapping segments. This is my preferred method for Triangulation at FamilyTreeDNA (overlapping segments and clear ICW grouping/Matrix). A subset of this is to use the LEEDs method to determine the four grandparents (and thus maternal and paternal groups) and extend to many other Matches who clearly have a Shared Match (ICW) consensus on one side or the other. Use “dots” or Notes to indicate maternal or paternal (or both) sides – these indicators absolutely help identify the side for more Matches.

Clustering often results in Clusters which can be clearly identified as maternal or paternal – this usually applies to all the Matches in each Cluster (but use caution with endogamy).

Note in all of the above, absolutely include parents, aunts/uncles in the TGs! Children and grandchildren should not be included, unless you’ve done other, detailed, analysis on their segments – in general, your descendants don’t add any value except in rare cases when comparing across company lines.  

If in doubt – leave it out!  Our ancestry (and DNA) sometimes includes some twists and turns. If you come upon something strange, revert to original mantra and check the Match segments against each other.

Take away: If you are sure of the same side, overlapping DNA segments Triangulate.

[11E] Segment-ology: Another Take on Segment Triangulation by Jim Bartlett 20230910

BLUF: MITx Course: Genetics: Population Genetics and Human Traits – Free Starts NOW!

Several years ago, I took their course: DNA – The Secret of Life; taught by Prof. Eric Lander – short bite-sized videos (some of which I watched several times); interspersed with a quiz; including labs and aside material – very close to a real life classroom experience – better than a Zoom (you can pause and rerun). Self-paced but covers a semester class. These MITx classes are available FREE! I highly recommend this class for anyone wanting to take a deep-dive into DNA. In one segment you’ll learn that the DNA base pairs are read in the 5 prime to 3 prime direction…

Link: https://www.edx.org/learn/biology-life-sciences/massachusetts-institute-of-technology-genetics-population-genetics-and-human-traits?utm_medium

[22BY] Segment-ology: Free DNA Classes from MITx TIDBIT by Jim Bartlett 20230816

A Segment-ology TIDBIT

This is an important point: The DNA Matching algorithms are based on finding a Shared DNA Segment. My DNA Segment matches your DNA Segment. We say: I match you; but, technically what we mean is my DNA matches your DNA – our DNA segments overlap and match – they match enough to satisfy the algorithm.

Above 15cM, the matching algorithms are designed to determine an Identical By Descent (IBD) segment. My DNA is identical to your DNA (all the SNPs are the same) over enough DNA that it can only be that way because we both got that segment of DNA from the same Ancestor. This is the foundational concept of autosomal DNA testing.

If a person only shares one IBD segment with us, we call that person a Match. We match the Match. We are basically equating the Match to the Shared DNA Segment. And most of our “Matches” share only one IBD segment with us. But not all…

Some of our “Matches” share two or more DNA segments with us. In these cases, we need to be careful how we speak. Each of these Shared DNA Segments is an independent event. Most of the time, multiple Shared DNA Segments will be from the same Common Ancestor, but that’s not a requirement of the biology. From my spreadsheet of over 20,000 shared segments, I can attest that there are many instances of multiple segments from one Match coming from different Ancestors (as well as many instances of Matches who are genealogically related to me in multiple ways).

I raise this point because I found myself assigning my 3C Match with 6 Shared DNA Segments to our Common 2xG grandparents. That is, in my spreadsheet, I assigned all 6 segments to the same 2xG grandparents. Analyzing each of these resulting Triangulated Groups, I found one that was “off”, “strange”, “out of kilter”… The other Matches in that TG were related to me on a different line. A little investigation into my 3C’s Ancestry revealed we were also 7C on a different line.  

I also raise this point to illustrate the importance of segments in genetic genealogy.

The point here is that we don’t really “match” a Match, we only match a part of their DNA.

Notwithstanding… like most of us, I will continue to say that “I have a Match” and that “I match person A”. It’s just important to remember that part of our DNA matches part of our Match’s DNA.

[22BF] [ Segment-ology: We Match Segments, Not Matches TIDBIT by Jim Bartlett 20230813

Bottom Line Up Front [BLUF]: Yes, but caution.

Here is the original statement that prompted this blog post:

The chance that three fourth cousins will all share the same matching segment is practically zero.

A bold statement – repeated several times – that has implications for Triangulated Groups. It appears this was part of the education material provided by AncestryDNA for their DNA Circles feature [Hat Tip to Debbie Kennett – the material is no longer online].

This means you and two 4C Matches sharing the same matching segment [all three of you descending from 3 different children of the Common Ancestor].

Mitigating factors:

1. Shared DNA segments in a Triangulated Group (TG) are rarely “the *same* matching segment”. We are almost always talking about overlapping segments of different sizes. So that gives some wiggle room. Maybe the odds are just small (not practically zero) with a group of different sized segments in a TG.

2. As Debbie pointed out to me, these were simulations by Ancestry, using “perfect” data. In genetic genealogy our data is usually somewhat messier than simulated data, so there is even more wiggle room. Maybe the odds are on the low end…

3. Another factor is that the data has grown substantially since the simulations were done for the Circles feature. The information has been removed.

The bottom line for me becomes: If you find 4C Matches in one TG from more than two other children of the Common Ancestor, take a closer look at it. It is possible, but there may be other factors at play.

Segment-ology CONCEPT – For Matches forming a TG (overlapping segments in a range), the odds decrease with each generation going back and with each additional child of the Common Ancestor. Take a critical look within TGs beyond 3C Matches spread over more than 2 other children. The odds are very small with Matches from 3 other children (total of 4 children).  This is not a “rule”.

Important Note: This does not mean that we cannot have DNA Matches from 4 or more children. We can! Instead of a double negative let me say: We can have 4C Matches from more than 3 other children of the Common Ancestor – we can have 7C Matches from 5 other children of the CA. It just means that there is more than one segment (TG) involved.  Over the different children, we should expect to see several TGs. We can have over a hundred Matches in a TG going back to 7XG grandparents, for example. We just need to carefully screen for the number of children per TG.

Takeaway: It’s hard to have a hard “rule” on this subject. However, it makes sense to pay attention to our data. The further back we go (in generations), the more constrained our options become.

I’m inviting discussion on this Segment-ology CONCEPT, and on your experience with TGs and numbers of Common Ancestor children.

[08E] Segment-ology: Can Three Fourth Cousins Share the Same Segment? By Jim Bartlett 20230812

A Segment-ology CONCEPT and Thought Stimulator

Per Wikipedia: A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup is a group of similar haplotypes. Your atDNA segment from an Ancestor is likewise a group (or string) of alleles (SNPs) that is inherited from a single parent – an atDNA haplotype. The Match segments in a Triangulated Group (TG) have this same string of SNPs – they have matching shared DNA segments – and this group would then be a Haplogroup (Hg).

A Triangulated Group of segments would be a Haplogroup.

Wikipedia also notes that in human genetics, the haplogroups most commonly studied are Y-Chromosome (Y-DNA) haplogroups and mitochondrial DNA (mtDNA) haplogroups, each of which can be used to define genetic populations.

In exactly the same vein, a Triangulated Group (TG) defines a genetic population. It’s the population of descendants who carry the same segment of DNA passed down by an Ancestor. DNA test takers in this population have shared DNA segments with the same string of SNPs – they match each other!

An mtDNA Hg is often many thousands of years old (because the mtDNA rarely changes). A Y-DNA Hg is usually somewhat closer, and with a Big-Y test, is often found within a genealogical timeframe. My estimate is that an atDNA Hg (a TG) is usually 5-9 generations old – generally within a genealogical timeframe. We could argue that a TG Hg is a better tool than Y or mt. For me, it is a very good tool. In any case, each DNA Hg tool has strengths in genetic genealogy.

Note that the process of Triangulation culls out most, if not all, false shared segments. A few false Match segments (under 15cM) may slip in; but your own DNA, as the base in a TG, is true. If such an under-15cM Match is critical to you, you need to check for Triangulation with that Match segment as the base.

MUSING….

Dr. Tim Janzen – one of the earliest pioneers in atDNA (and my early mentor), has often advocated for a database of unique atDNA segments from our Ancestors. I used to think of this as a giant TG database and wonder how we would describe each TG. Now I think it would be an atDNA Haplogroup database, but still wonder how we would describe each Hg. Each segment would be unique to a specific Ancestor and would be on a specific chromosome (with start and end points). Note the chromosome could be maternal or paternal, depending on each Match’s ancestry. This segment would manifest itself in a TG, with shared segments from other descendant Matches. Each Match would likely have his or her own unique TG. These TGs taken together would represent an atDNA Hg from that Ancestor.

NB: if we can phase our data, we could actually record the SNP alleles (ACGTs) in each TG (or atDNA Hg)! Alternatively, by comparing raw DNA data among the Matches in a TG, we could probably determine the individual the SNPs. Remember your TG segment is the equivalent of phased DNA.

This post is about an atDNA Haplogroup. It’s a concept to think about. Your thoughts are welcome here.

[14B] Segment-ology: A Triangulated Group is an atDNA Haplogroup by Jim Bartlett 20230802

When working with Matches on one side (Maternal or Paternal), segment Triangulation is a snap. Overlapping segments are all you need! The overlap should be at least 7cM, and more is better.

The basic rules to form Triangulated Groups, were designed to insure your overlapping shared DNA segments were on the same side – in other words on just one of your chromosomes. This means, from your viewpoint, the overlapping segments were both (or all) on your maternal *or* paternal chromosome. It didn’t matter which side it was on for your Match. You can have lots of shared segments on one chromosome, but some may be on your maternal chromosome and the others on your paternal chromosome. It is virtually impossible for Match A’s shared segment on your maternal chromosome to also match Match B’s shared segment on your paternal chromosome. So the requirement is/was to compare Match A and Match B to insure they match each other – and are thus on the same chromosome with you.  *IF* you already know Match A and Match B are on, say, your maternal side, then their shared DNA segments with you would be on your maternal chromosome, and there is no additional need to compare them to each other – they Triangulate.

I am sure, in the grand scheme of genetic genealogy, that an occasional glitch could occur. I’d estimate this as way less than 1% probability.

FTDNA has maternal and paternal buckets which appear to be pretty accurate. If the companies designated a “side” and allowed us to filter Matches based on that side, it would sure speed up segment Triangulation. Just look at a spreadsheet for natural crossover breaks in each chromosome.

In the meantime, if you can designate your Matches as Maternal or Paternal in some way (compare to a parent’s test, ethnicity, shared matches, etc.), you can use that info to filter your Matches and ease the segment Triangulation process. There’s still a lot of work to do, but this should ease the process some.

[10E] Segment-ology: Triangulation on a Side Is a Snap by Jim Bartlett 20230730