About jim4bartletts

I've been a genealogist since 1974; and started my first Y-DNA surname project in 2002. Autosomal DNA is a powerful tool, and I encourage all genealogists to take a DNA test.

Shared Clustering – A Great Tool!

A summary of some different Clustering programs is here. I’ve used, and liked, most of these programs, and I want to highlight one of them here.

Shared Clustering by Jonathan Brecher is a good, flexible tool – it does what I want, quickly. It doesn’t have the glitz of Genetic Affairs or other features offered by DNAGedcom Client. But it gets the job done for me, efficiently, and it’s free. Some detailed steps at the bottom of this post.

Some comments on Shared Clustering:

– I used a 6cM threshold and downloaded all my 118,853 Matches (and Shared Matches) at AncestryDNA in 2 hr 34min.

– I then ran a Cluster report with a 90cM threshold in 2 seconds (that’s not a typo): 34 Matches in 8 Clusters.

– Each Cluster is assigned a number.

– Each Match is shown in one Cluster – the one with the most matches to other Shared Matches – the most “heat” in a heat-map program.

– AND all of the Correlated Cluster numbers are also shown for each Match. These are Clusters where the Match also has an affinity – the Match shares some Shared Matches with the rest; just not as much as in the Cluster it’s assigned to. This is very handy, because sometimes our known relationship with the Match would be a better “fit” in one of the other Clusters – feel free to use judgment and assign a Match to any Correlated Cluster you want. OR, if a Match shares two segments with you, assign it to two Clusters. Omygosh – that violates the Cluster “rules”! But this is your data now, use your own judgment and bend the rules a little – just don’t get too wild…

– I ran multiple other Cluster reports, each one took only a very few seconds.

– With a threshold of 28cM, I get 1105 Matches in 94 Clusters – in 4 sec. For me, that’s about one Cluster for each of my 5xG grandparents. Of course, it won’t fall out exactly this way, but that’s the general area of my Tree I’d be working in with these Clusters. Remember: Clusters tend to form on individual Ancestors.

-Each report includes a one-click link to each Match’s DNA page with me – very handy.

-All of the ThruLines Common Ancestors (CAs) are also included for each Match – a convenient check, if you haven’t already summarized each of them in the Notes. Or if you are just checking for new Matches among your ThruLines.

-Each report includes all of my Notes (into which I’ve already summarized ThruLines, other CAs and TGs).

-VERY IMPORTANT: I can modify as many of my Notes as I want in the spreadsheet, and then easily click to upload that info back to AncestryDNA (it overwrites the Notes that I’ve changed – WOW, what a time saver). This uploads in under a minute. Use this feature to summarize ThruLines CAs into your Notes (if you haven’t already), and upload that back to AncestryDNA. Use the “Upload Notes” TAB.

-ALSO IMPORTANT: I can use the “Export” TAB to download my AncestryDNA data, including Notes, to an Excel file, giving me an inventory of all my Ancestry Matches (without the Clusters or Shared Matches). This is my go-to file whenever I’m searching for an Ancestry Match (like from a name or email at GEDmatch). It’s much better than using the AncestryDNA search system. And the hyper-link means I am just one click away from my Match’s DNA page with me.

Some steps to get started:

Go to this page to download the program to your PC: https://github.com/jonathanbrecher/sharedclustering/wiki

Read the Home page, and then click on the download link on the right side (if you get a popup warning, tell your PC it’s OK)

Read the Introduction TAB, then select the Download TAB

You are now working from your own PC – enter your Ancestry username and password and select your test.

I click on “Slow and Complete”, but feel free to try each of the radio buttons. I set “Lowest centimorgans” to retrieve to 6cM and get all my 118,000 Matches in about 2.5 hours. Note where your file is stored. If you set “Lowest centimorgans” to 20cM , you’ll get all your “forth cousins” and closer in less than 10 minutes – this includes all the Matches who are used as Shared Matches.

After the Download is complete, select the Cluster TAB – the Saved Data File (from the Download) is usually shown by default, but you can also use files downloaded from other companies, if you want. The Cluster output file usually shows by default too – it’s the same name as the Saved Data File with “-clusters.xlsx” appended instead of “.txt” You can change the name of this file if you want – I usually append the default cM I’m using (e.g. 28) after “clusters” so I can save them all with different, recognizable, names. Just make sure both files (the Download “txt” file and the title of the new clusters “xlsx” file) are in the same folder. I’ve also set up a Clustering folder, and a sub-folder for the Shared Clustering program, and separate sub-sub folders with a date of the initial download file (e.g. 20191123) – so the Download and each of the Cluster runs would go in that (20191123) folder. A little work on organizing a file system really helps me remember what I’m doing….

Click on the “Cluster completeness” button of your choice; and type in the “Lowest centimorgans” box. Then hit Process Saved and wait about 2 seconds.

This Chart shows the relationship between the cM Threshold selected and the number of Clusters that result (for the Download of my data). Your results may vary, but the shape of the curve will be the same. The curve flattens below a 20cM threshold, because the Shared Clustering uses the Clusters at the 20cM threshold as a base and adds the other, smaller cM, Matches to the Clusters formed at 20cM. The smaller Matches (below 20cM) often have Shared Matches (all of whom are 20cM or higher), but there are no additional Shared Matches below 20cM. Experiment with your Download – it only takes a few seconds to change the Threshold cMs and get a new set of Clusters. NB:The Cluster numbers are uniquely formed during each Cluster report. They do NOT follow the Matches to other Cluster reports – they shouldn’t, because the new Clusters (formed on Ancestors) are different at different generations.

Jonathan monitors the Shared Clustering facebook page, and he’s always been very responsive. It’s good to visit that page and follow the conversations. And ask questions. And request improvement features.


I will try to post soon on my Walk The Clusters Back project, using Clusters that should be focused on different generations in my Tree – very successful.

If I’ve messed up anything in this review of Shared Clustering, I hope Jonathan Brecher and/or other readers will provide feedback in the comments.


[19C] Segment-ology: Shared Clustering – A Great Tool! by Jim Bartlett (20191129)

Grouping Matches – Try It!

A Segment-ology TIDBIT

We can group Matches several ways:

  1. Each Triangulated Group (TG) includes Matches who share the same Common Ancestor (CA). This is based on your DNA segment from an Ancestor, which other Matches also share. 23andMe, MyHeritage and GEDmatch all have tools for Triangulation.
  2. Clustering includes Matches who share multiple Shared Matches with each other – they tend to be based on the same Ancestor. The Leeds Method focuses on 4 groups representing our 4 grandparents. This is based on the probability that groups of Shared Matches will probably have the same Ancestor. When the lowest threshold is used (6cM), all of the company Matches are included and the Clusters tend to approximate a one-to-one relationship with TGs. This is a good tool to group our Matches at AncestryDNA and FamilyTreeDNA. I blogged about some Clustering programs here.
  3. We can also form Clusters based on ethnicity, geography, Haplogroups, etc., but, in general, these will not be as precise as TGs and Shared Match Clustering. These Clusters are, however, often very helpful in homing in on a CA.

Groups can help us in several ways:

  1. Everyone in a group should have the same objective: finding the CA. There is synergy in a group; and working together often results in a better outcome. One person’s Brick Wall or bio-Ancestor (vs. an NPE) may be in the Trees of other Matches in the Group.
  2. Close Cousins and their CAs with you provide a beacon toward the more distant CA, and limit the possibilities that would otherwise need to be explored.
  3. Once several Matches in a group agree on a CA, that CA line can be imputed to the other Matches. Many times I have searched a Match’s Tree for a specific Ancestor (highlighted in the Cluster), and found it! I’ve also communicated with Matches with no/small Trees and asked specifically about a surname and gotten positive/helpful responses.
  4. Use Clustering to form groups at FTDNA, MyHeritage and 23andMe, and use them as a basis for TGs – Triangulation goes much more quickly when you only compare segments that will probably Triangulate.

We can form Triangulated Groups at 23andMe, MyHeritage, GEDmatch, and, with a Clustering pre-start, at FamilyTreeDNA – but those companies, generally, do not offer much in the way of genealogy tools, and only a few of the Matches have robust Trees. On the other hand, AncestryDNA has a lot of good Trees, and great tools like ThruLines, but no DNA segment data – however, we can do Clustering. DNA and No Trees; OR Trees and NO DNA – it’s frustrating… So how can we merge the TGs and AncestryDNA’s Clusters?? More on this later…

BOTTOM LINE: We need both Triangulated Segments and Triangulated Genealogy to be in sync (reinforcing each other) before we can have confidence in our conclusions. One without the other is incomplete research.


[AQ] Segment-ology: Grouping Matches – Try It!  TIDBIT by Jim Bartlett 20191128

Extending the MRCA of a TG through Clusters

A Segment-ology TIDBIT

Triangulated Groups (TGs) are one way to group your Matches – grouping Matches who share overlapping DNA segments with each other. The DNA segment represented by a TG, is passed down to you from one of your parents, and from more distant Ancestors on that side. As we find Most Recent Common Ancestors (MRCAs) with Matches in a TG, we begin to learn which ancestral line passed down the TG segment – a Common Ancestor.

Clustering is another way to group your Matches – grouping Matches who share other Shared Matches with each other. The Matches in a Cluster also tend toward a Common Ancestor.

The companies where Triangulation is possible generally do not have many robust Trees. And so the TGs do not have many MRCAs. AncestryDNA has many robust Trees and a ThruLines tool that determines many Common Ancestors (CAs) , but does not provide the DNA data needed for Triangulation.

Is there a way to combine the best of both worlds? I think there is. TGs and Clusters should be grouping on the same thing – an ancestral line – a Common Ancestor. When a TG and a Cluster clearly have some of the same Matches, I think the deeper MRCAs in the Cluster, can be imputed to the TG.

This is another method of Walking The Ancestor Back (WTAB) in a TG. You already have a TG with some MRCAs along the same line. The Most Distant Common Ancestor (MDCA) in a TG usually represents a couple, one of whom passed down the TG segment. The next generation back has only two possibilities: the paternal or maternal side of the MDCA.

The MRCAs in a Cluster aligned with the TG provide a strong clue in reinforcing and extending the CA for a TG.


[22AP] Segment-ology: Extending the MRCA of a TG through Clusters TIDBIT by Jim Bartlett 20191118

Ahnentafel 37P – Breaking Through a Brick Wall

This is the first in what may be a series of Ancestor Stories that have been made possible by DNA.

Background on Thomas NEWLON, Ahnentafel 36

This story starts on firm ground with my ancestor, Thomas NEWLON (my Ahnentafel 36). I have solid evidence of Thomas NEWLON. We have 3 matching Y-DNA kits from men who descend from him and his father which prove his NEWLON line, at least back to his father, James NEWLON. The Y-DNA Haplogroup is R1b1a2.

Per the Personal Property Tax Lists (PPTL) of Loudoun Co, VA, Thomas NEWLON is listed 1788-1802 (adjacent to his father James). If we assume that he was, say, 19 in 1788 (many fathers cheated a year or two on their son’s age to avoid paying taxes from the 16th birthday), his birth year would be 1769. This is a good “fit” as his parents, James NEWLIN and Catherine BENNETT were married 7 Apr 1768 in Chester, PA. The NEWLONs in this part of PA were Quakers. At a Warrington Monthly Meeting on 11 Jun 1768 James NEWLAND was disowned for marrying out. I don’t have any records for the next 20 years (until the 1788 Loudoun Co, VA PPTL). Many say some of Thomas’s siblings were born in Culpeper Co, VA, but I’ve not seen any such records. In any case, I have the records showing Thomas NEWLON was living in Loudoun Co, VA from 1788 to 1802.

Thomas NEWLON’s eldest child was Cecelia, who was born 3 Aug 1793 per her obituary. This means that Thomas married someone probably in 1792, and almost certainly in Loudoun Co, VA where he was living. Let’s say his wife was born in 1774, and married at age 18 – not uncommon for that time period. We have several pieces of later evidence that her family was also living in Loudoun Co, VA at that time and at least up until about 1810.

From his 1813 Will, Thomas NEWLON’s first four children were Cele [Cecelia] 1793, William 1795, John 1798 [my ancestor] and Sarah 1800 – the birth years from other evidence. In 1802 Thomas NEWLON is listed on the PPTL of both Loudoun Co, VA and Harrison Co, VA, so it’s safe to assume this family of six, moved to Harrison Co, VA in 1802.

Thomas NEWLON is in the Harrison Co, VA PPTL from 1802 to 1813. Thomas wrote his Will on 7 Jul 1813, and the 1814 PPTL listed: Thomas NEWLON (heirs). His will had specific instructions for his first four children, and named three more children and wife Sarah. All seems in order… Except for the Harrison Co, VA 20 Jul 1805 marriage record for Thomas NEWLON and Sarah POWELL. And it turns out Sarah was the widow Sarah POWELL – her maiden name was Sarah STROTHER (daughter of Reuben STROTHER and Susannah BARTLETT) and she had married 17 Apr 1787 in Loudoun Co, VA to Henry POWELL who died c1804. Sarah POWELL is in the Harrison Co 1804 PPTL and “Henry POWELL heirs” are listed in the 1805 PPTL. Sarah brought 5 to 7 POWELL children to the NEWLON household when they married in 1805. What a packed house…

Thomas NEWLON’s wife

But back to the story – who, then, was Thomas NEWLON’s first wife? She would be the mother of son John NEWLON, my ancestor, and therefore whoever she is, she’s also my Ancestor. John NEWLON is my Ahnentafel 18; Thomas NEWLON is my Ahnentafel 36; and his first wife is my Ahnentafel 37.

I have searched for any clues since the 1980s, and others had been looking long before then… nothing. One researcher claimed he had proof she was Martha JANNEY, but went to his grave refusing to show the evidence. [Many people with online Trees, show Martha JANNEY as Thomas’s first wife. I spent a day at the history library at WVU in Morgantown, WV (my alma mater), where some said the JANNEY proof had been preserved… nothing. I searched the JANNEYs in the Loudoun Co, VA courthouse and several libraries… and found nothing. Well, I did find that the JANNEY’s were Quakers and most lived in one area of Loudoun Co; and almost none had Slaves (Slavery was against their religion). The only clue I ever found was in the death record of her son, William NEWLON who died 21 Sep 1881 Simpson, Taylor Co, WV. It listed his parents as Thomas and Susan. Informant – son, C L NEWLON [Chapman L]. Susan! Well a small thread to hang onto.

I also note that Thomas’s first child with second wife Sarah was a girl, whom they named Susannah. And all but one of Thomas’ first four children named their first daughter Susannah. So, I’m convinced Thomas NEWLON’s first wife was named Susan, or Susannah.

So, Thomas NEWLON’s first wife was Susan…

During all these decades of research, most of us kept running into the same family story: A year or two after settling in Harrison Co in the western part of VA in 1802, Thomas NEWLON’s wife decided to return to her parents’ home in Loudoun Co, VA to get a Slave to help her “on the frontier”. She and son William (then maybe about 8 years old) rode horseback to Loudoun Co. While at her parents in Loudoun Co, she was poisoned and died (the Slave family did not want to be torn apart). What a tragedy that was! This story would explain the marriage of Thomas NEWLON, with 4 children, to Sarah STROTHER POWELL in 1805.

An 1878 Newspaper article in the Leesburg, VA Mirror contained a brief notice from “The Clipper” [in MO] of the death of Mrs. Cecelia McPHERSON, with occurred in Ralls Co: The deceased was … born in Loudoun Co, VA 3 Aug 1793, the oldest of a family of Wm [sic] NEWLON and her childhood was spent in the wilderness of the western portion of that state. In 1808 she returned to the place of her birth and was married there 1 Apr 1810 to Stephen McPHERSON, whose faithful consort she was until his death in 1847.

This article explains a lot. Cecilia’s birthdate; she was the eldest; she returned to Loudoun Co, VA in 1808 [when she was 15 years old – almost certainly to live with her grandparents – probably on Susan’s side, as Thomas’s parents, William and Catherine, were near the end of their lives. NB: Wm [sic] NEWLON is clearly wrong – wrong in the original MO newspaper, or wrong in the VA newpaper, or wrong in a subsequent transcription. Cecelia’s father was Thomas NEWLON.

My Ancestral Brick Wall: Susan LNU c1774-c1802

So we are looking for a Susan [Last Name Unknown]; born c1774; married c1792 in Loudoun Co, VA (age 18); had 4 children: 1793, 1795, 1798, 1800; moved from Loudoun to Harrison Co, VA c1802; died c1804 (age 30); and her family was in Loudoun Co, VA at least from 1792 to 1810 and had Slaves.

I was stuck on this Brick Wall until 2017, when I turned to autosomal DNA for more clues.

Triangulated Group [01S24]

I’ve been Triangulating shared segments since about 2011, and had already formed about 370 Triangulated Groups (TGs) which covered basically all of my DNA – all 45 chromosomes. Thomas NEWLON and Susan are my 3xGreat grandparents – at the 4th cousin (4C) level. So I looked at all the TGs with closer cousin-Matches with known Common Ancestors (CAs) pointing to my NEWLON ancestry. Several of these TGs already had more distant cousins on the NEWLON side, so I set those aside. I finally decided to start with a large TG that I called [01S24].

TG [10S24] already had four Matches who were 4C from Thomas NEWLON. The TG included over 100 Matches, and none had been found to go back up the NEWLON ancestry. In addition, there were over 25 Matches from AncestryDNA who had uploaded to GEDmatch or tested at another company and I knew their Ancestry name. I had the AncestryDNA Helper installed in my Chrome browser, so I was able to visit each of these Matches and, in the lower left of their page, I could download all of their Ancestors to a spreadsheet. I did this, and then combined all the spreadsheets into one and sorted on the Ancestors.

I descend from a CUMMIN/GS

The clear Surname “winner” was CUMMINS/CUMMINGS – 9 of my AncestryDNA Matches had CUMMIN/GS ancestry. Bingo! This was a new surname for me. I then searched my FamilyTreeDNA Matches for this surname. In [01S24] 6 of them had CUMMING/S. At MyHeritage, I have 12 Matches who Triangulate in [01S24] and have CUMMIN/GS ancestry. I messaged my 23andMe Matches in [01S24] and 4 of them reported CUMMIN/GS ancestry. Yes, some of the Matches had tested at multiple companies, but some at each company were new – additional evidence that, somehow, CUMMIN/GS was in my Ancestry, and on TG [01S24].

Next was the process of creating a CUMMIN/GS Tree. A number of my Matches had already traced their line back to Alexander CUMMINS b 1677 Northumberland Co, VA, d 1738 Prince William Co, VA; m 1694 Northumberland Co, VA Sarah MUTTONE/MUTTONE b 1677 Northumberland Co, VA, d about 1738 too. Several of their children died in Fauquier Co, VA. Two things soon became clear: 1) many of their descendants went to Fauquier Co, VA, and some went to adjacent Loudoun Co, VA; and 2) there is a lot of conflicting data about this family (particularly with people who can trace back to Fauquier and Loudoun and then accept other peoples Trees who say those CUMMIN/GS were from Scotland or MD). The records are few and, it appears to me, a lot of guesswork had taken place. But the DNA tells me most, if not all, of the CUMMIN/GS in Loudoun and Fauquier Co are related to each other – at least on segment [01S24]. Within [10S24] most of the Matches shared a DNA segment with most of the others. And I think, as I share this story with all of the Matches in TG [01S24], and they confirm that they match each other (and possibly others), they will come to the same conclusion that they probably, somehow, descend from Alexander CUMMINS and Sarah MUTTONE. The weight of the evidence was that my Ancestor Susan was a CUMMINGS. Other, far less likely, alternatives are discussed below.

My Ancestor, Ahnentafel 37, was Susan CUMMINGS c1774-c1802 (hypothesis)

Next, I focused on the CUMMINGS in Loudoun Co, VA. In this effort, Pat Duncan was a big help. She has transcribed many of the Louduon Co, VA early records and published a series of indexed books. She graciously emailed me the early Tax Lists for CUMMIN/GS, and pointed out there was only one man who had Slaves in the time period I was looking at: John CUMMINGS.


There were two John CUMMINGS in the Tax Lists – one had stud horses and race horses and Slaves, and the other did not. In working through all the records I came up with a John CUMMINGS in the Loudoun Co, VA Personal Property Tax Lists from 1787 to about 1811, almost always with horses and Slaves. On 25 Mar 1811 John CUMMINGS and wife Jane of Loudoun sold land. On 12 Apr 1813 there are two records in Loudoun Co, VA:

  1. John CUMMINGS married Margaret EMERSON
  2. John CUMMINGS of Culpeper Co, VA to Margaret EMMISON of Loudoun – a marriage contract for Margaret to receive a child’s portion in lieu of dower for sake of John’s children by former wife.

Searching back through the records we find John CUMINGS married Jane JOPSON 23 Jun 1780 in Newtown, Bucks Co, PA. There are other Bucks Co, PA records from 1781 to 1785 with John CUMMINGS, including the 1785 Will of Richard JOPSON which mentions daughter Jane CUMMINGS.

John CUMMINGS b 1746 VA; d 1826 Culpeper Co, VA

Other records for John CUMMINGS, to trace his life, have been hard to find. Most researchers, including LDS FamilySearch record 29QJ-C42, have John CUMMING born 1746 Ireland; died 10 Oct 1826 Culpeper Co, VA. And John CUMMINGS is in the 1820 Culpeper Co, VA Census (born before 1775, wife born before 1775, 7 Slaves). Given the many DNA Matches to the CUMMIN/GS in Loudoun and Fauquier Co, VA, I’m pretty sure this John CUMMINGS was born in VA, not in Ireland. However, I have not found a record, yet, that indicates a birth year of 1746. So to summarize so far:

Susan CUMMINGS born c1774; married c1792 in Loudoun Co, VA (age 18); had 4 children: 1793, 1795, 1798, 1800; moved from Loudoun to Harrison Co, VA c1802; died c1804 (age 30); and her family was in Loudoun Co, VA at least from 1792 to 1810 and had Slaves.

John CUMMINGS b 1746 VA; d 10 Oct 1826 Culpeper Co, VA; m 23 Jun 1780 Bucks Co, PA Jane JOPSON (b 1753); moved to Loudoun Co, VA about 1787, where Jane died in 1811; John m 12 Apr 1813 Loudoun Co, VA Margaret EMERSON, and they then lived in Culpeper Co, VA.

But who was Susan’s mother?

Susan was born about 6 years before John CUMMINGS married 1780 Jane JOPSON. And if John CUMMINGS was really born in 1746, he would have been 34 years old in 1780. That’s not usual for this time and place. I believe John CUMMINGS had an earlier wife – someone he married before 1774 and who probably died c1778 – who was the mother of Susan. I still don’t have a clue as to who that first wife might be, but I’m still getting Matches who are cousins on the CUMMINGs line. I’m pretty sure John CUMMINGS did have an early wife and that Susan CUMMINGS was his daughter. That’s my hypothesis.

My Ancestor, Ahnentafel 74, was John CUMMINGS b 1746 VA; d 1826 Culpeper Co, VA

I’ve now built a tentative Tree connecting John CUMMINGS back to Alexander CUMMINS and Sarah MATTONE. And I’ve connected most of the 17 Matches in [01S24] into this Tree. Based on the Triangulated Group, I’m convinced that all of them tie back to Alexander and Sarah somehow. And I’m sure that other Matches in [01S24] will be found to have this ancestry, too. I’m also sure, based on the number of overall Matches, and the fact that they the tie to the CUMMINS lines at different generations (from 5th to 8th cousins) that the DNA came down this CUMMIN/GS line to segment [01S24]. In [01S24] the DNA does not go back on any of the wives’ lines, it goes all the way back to Alexander CUMMINS. The fact that this DNA comes down the all-male line for 3 generations is why I’m seeing so many Matches with CUMMIN/GS ancestry in this segment. Other TG segments that go back to Thomas NEWLON and Susan CUMMINGS may well go further back through Susan’s mother. Then I can repeat this process all over and search for the surname and Ancestor for that Brick Wall. As the old genealogy saying goes: you solve one Ancestor and it generates two more to solve.

NEXT: Search for Ahnentafel 75 – Susan’s mother.

I hope this story shows the integration of Y-DNA and atDNA tools with traditional genealogy researching tools. This story could not be told without a good mix of both.


  1. Does Susan have to be a CUMMINGS? No, her mother could be a CUMMINGS and her father could be some other surname… However, almost all of my Matches in [01S24] share 20 to 46cM with me. That’s a lot for a 5th cousin, much less a more distant one. So I’m pretty sure Susan is a CUMMINGS.
  2. I estimate that about 24 of my 371 TGs will be Ancestral to Thomas NEWLON and Susan CUMMINGS – say 12 TGs for the NEWLON side and 12 TGs for the CUMMINGS side. 6 of them will go back on John CUMMINGS’ side (including [01S24]); and 6 of them will go back through the first wife of John CUMMINGS. Those are the 6 I need to identify and start working on. NB: Each of the other 15 3xGreat grandparent couples will also have about 24 TGs. Of course, DNA is random, so our actual experience may vary a little.


[23-37P] Segment-ology: Ahnentafel 37P – Breaking Through a Brick Wall by Jim Bartlett 20190804

How Does ThruLines Work?

A Segment-ology TIDBIT

To understand how it works, we need to think like the ThruLines algorithm does. I’m pretty sure the algorithm has three parts: 1) start with two DNA Matches (you and someone else); 2) find a Common Ancestor in their Trees*; 3) find and report the path from the CA down to you and the path down to your Match.

The TL algorithm has no way to check to see if the ancestral lines back to the CA are correct or not (witness the TL reports that report incorrect genealogy). It doesn’t know if the lines are even biologically correct or not – it relies on what you and your Match have entered into your respective Trees. TL also does not check spelling of the names of the descendants from the CA – you could list your grandfather as Rumplestiltskin JONES, or Bio Father, and that is what TL will report.

Also note that even if all the information in a TL report is correct, there is no guarantee that the identified CA is the Ancestor who passed down the shared DNA segment. As reported here, I found at least 10% had a shared DNA segment that did not come from the CA.

Edit 20190801 *sometimes other “3rd-party” Trees are used to complete the linkage from a Common Ancestor down to you and/or your Match.

[22AO] Segment-ology: How Does ThruLines Work TIDBIT by Jim Bartlett 20190801

A Few ThruLines Are False, and Some are Misleading

A Segment-ology TIDBIT

I made a spreadsheet of my 1,820 ThruLine Matches – to track and analyze them all. I found 86 were questionable (some of those 86 were clearly wrong, and others were iffy – I just didn’t have the information (or time) to sort it out. 86 is roughly 5% of the total, which means I agreed with 95% of my ThruLine Matches. Note a few of my Matches are double counted because they shared more than one Common Ancestor with me.

A high percentage of ThruLine Matches were good, giving me confidence in this tool.

Of my ThruLine Matches, 145 of them had uploaded to GEDmatch (or tested at other companies). I found one of the 145 (1.5%) had a false Shared Segment with me – it didn’t match a Triangulated Group on either side. I also found that 15 of these Matches (10%) with segment info had TG segments with me which were on a different one of my grandparents than the ThruLine Common Ancestor. This is not necessarily an error by ThruLines (the Match is very likely still a genealogy cousin on the ThruLines Common Ancestor), but in each case the DNA Shared Segment indicated we should have another Common Ancestor on a line from one of my other grandparents. Most of the 15 Matches were on the wrong side – the ThruLines Common Ancestor was on one side, and the Shared DNA Segment was on the other side.

So, from this small sample, about 10% of the ThruLines Common Ancestors may be misleading from a genetic (or chromosome mapping) point of view.


[22AK] Segment-ology: A Few ThruLines Are False, and Some are Misleading TIDBIT by Jim Bartlett 20190729e

ThruLines Helps with Y-DNA and mtDNA

A Segment-ology TIDBIT

When ThruLines finds a Common Ancestor between you and a Match, it provides the picture: The Common Ancestor at the top with the line of descent to you and the line of descent to your Match. Click on the left side of your Match’s Profile to open this diagram of descent.

Pay attention to this line of descent to your Match. Is it an unbroken all-male line down to the Match (every man would have the same Y-DNA, including the Common Ancestor), or is it an unbroken all-female line down to the Match’s mother (every person would have the same mtDNA back to the Common Ancestor’s wife (usually also a Common Ancestor)?  I’ve found a number of these cases, some to be very important to my research. Two of my ThruLine Matches carry the mtDNA of two distant female Brick Wall Ancestors. These are generally very hard to find – but it’s obvious from a quick look at the ThruLine diagram. Three of my ThruLine Matches carry the Y-DNA of our Common Ancestors. Sometimes the Match is excited about helping establish the mt or Y DNA haplogroup or “signature” of our Common Ancestor – other Matches couldn’t be bothered… I offer to help the ones willing to test.

And even if the unbroken all-male or all-female line only comes down to the Match’s parent or even to the grandparent – an interested Match may know of close, living relatives who may continue the line and be willing to test. For me, it’s certainly worth mentioning to the Match.

ThruLines may help you find mtDNA or Y-DNA candidates that might be helpful to you.


[22AJ] Segment-ology: ThruLines Helps with Y-DNA and mtDNA TIDBIT by Jim Bartlett 20190729d