Jim Bartlett has been a genealogist since 1974. He started the BARTLETT DNA Project at FamilyTreeDNA in 2002. Soon thereafter he began teaching DNA to various genealogy groups in MD, VA, DC, WV, etc.  In 2010 Jim took his first autosomal DNA test at FamilyTreeDNA, followed shortly by atDNA tests at 23andMe and AncestryDNA. Jim has become a huge fan of the Triangulation process and chromosome mapping – the ultimate human puzzle. This site was set up to document information about segments and autosomal DNA.

17 thoughts on “About

  1. I am new to DNA and have tested at Ancestry.com and FTDNA. I greatly appreciate all this information. I intend to study it. I am 80 and my “forgetter” works over time so I need the help. I live in South riding VA just outside od DC and I see you do a lot of lectures in this area so I would be interesting in coming to one of your lectures.


  2. Jim – I remember reading that you’ve mapped over 90% of your segments to the contributing ancestors. I’m doing okay at the grandparent level, thanks to close relatives who have tested, but progress is slow after that since it is so difficult to triangulate with 5th-8th cousins. I would love to see a blog post on advanced techniques for finding MRCAs and solving segment matches with more distant cousins. Thanks,


    • Rich, I think the secret is in contacting every Match in a TG; and trying to get them to communicate with each other. None of us knows all the answers – there’s a good chance that some of our Matches in a TG could find the CA among them, without my input – perhaps they’d come up with evidence on the other side of my brick walls and/or NPEs that I didn’t realize. We need to use the synergy of a TG team.


  3. Jim,

    I am having trouble understanding a particular nomenclature in the TG Tree that GEDmatch built for me. I have searched through your explanations in this blog and have been unable to find an answer.

    In the boxes with the red outline I understand everything but the bottom line. An example is “3(0,1)>4(1,2).” Can you help me with this?


    Jim Campbell


    • Jim – please disregard those cryptic numbers in the bottom row. They were used by the programmer to help set up the graphic. They were used to place and link the boxes, and should have been removed before the utility went public.


  4. Do you analyze GEDmatch results for a fee? If yes, what is the hourly rate? If no, can you recommend someone? I am trying to analyze my results to identify my great great grandfather. Y-DNA testing has not helped us. Three of us on GEDmatch are 2nd cousins (we are all women) and there are more cousins from different children of my great grandfather on GEDmatch. With three 2nd cousins, in theory shouldn’t it be easy to zero in on the common ancestor who is our great great grandfather? The problem is the analysis as I am finding it difficult to do.


    • Maralaina,
      I am fully retired and devote most of my spare time to DNA and genealogy. One of my goals is to teach others how to analyze atDNA data. I have spent the last 6 years analyzing mine and am now working on my father’s atDNA. To do it all for a person takes a major time investment. I don’t charge for what I do, but I also don’t analyze other’s DNA. You might try http://www.ISOGG.org/wiki – click on the autosomal TAB and look for the list of resources. However, you are on the right track. Find all the shared segments (from your Match list), which also match (Triangulate) with your cousins from your great grandfather. In theory half of those Triangulated Groups will be on your great grandfather’s maternal side, half of them will be on his paternal side. Work with all of those Matches to see where they have a Common Ancestor. At this point it’s all about the genealogy – the DNA can only help so far.


    • Rebecca, Thanks for the link to your work. Just about everything you say in your post is the same thing I’ve been saying for years – and so I like your article and the direction you are emphasizing. Many good pieces of advice in your article.
      If you’ve read all of my blog posts, you’ll understand that I think Triangulation and Triangulated Groups (TGs) are just fine. In fact one could substitute TG for IBD in your Article. My TGs are the same as your IBDs, with all of the same rules as well as cautions (many of which I’ve similarly stated). There are two types of Triangulation: genetic (or segment) Triangulation (TGs formed from sufficiently overlapping shared segments from widely space cousins – this is a purely mechanical process and does not require genealogy); and genealogy (or ancestor) Triangulation (getting at least 3 widely spaced cousins to agree on the Common Ancestor (CA) – and in the end getting most of the Matches in a TG to agree on the same CA line). Since TGs have to be on either a maternal or paternal chromosome, some genealogy is required to assign them to the proper side. Triangulation does not lead to errors, it leads to rock solid chromosome mapping. Any process (including “solving IBDs”), if done incorrectly can lead to errors. I’ve been a very active genealogist since 1974 – and an active genetic genealogist since 2002. My atDNA spreadsheet now has 259 TGs with CAs, 102 TGs w/o a CA, and 55 “fabricated” TGs in the gaps to “fill up” all 45 of my chromosomes. I have many TGs with multiple CAs identified with the Matches; but only one ancestral line is linked to each TG – that is one of my ancestors, at each generation, going back to the “founder” of the TG. There is, in fact, a single ancestor who started each full TG. Ancestral to that, the TG does not exist intact, it was different, smaller segments from different ancestral lines. Some of our Matches, with smaller shared segments can, however, descend from more distant ancestors of that CA (but not with the full TG segment) – this leads to a subset TG with it’s own, more distant, CA. Our TG Matches can also have MRCAs with us all along our own ancestral path. This is why “walking the ancestor back” is an important method to “solving” a TG (along with genealogy Triangulation). With all of the new Matches that are now (2017) pouring in, we should be getting cousins at all levels in our TGs.
      Thanks again for your comprehensive article that applies equally to solving IBDs/TGs.


  5. Jim,
    I just found your site referenced on Gedmatch. It looks great.
    I have been working on a way to identify shared segment groups in Ancestry matches. It appears that it should work.
    The basic idea is that we can see what must be shared segment groups by just looking at the “In Common With” data. For example, I might see that Bob, Jane, Bill, and Mary all match each other as well as me. The simplest explanation is that we all have the same shared segment.
    So I can pull out all of my shared match data using the DNAGedcom tool and mine the data for groups that overlap with each other. There are fancy cluster analysis tools for doing this but I have found an Excel pivot table is a good start.
    There are three problems, though.
    1) If I match someone in more than one segment, they will be members of more than one shared cluster group and it will appear that the groups are actually a single group. This is easy to solve- I start by removing all of the individuals who match me in more than one segment.
    2) I match Bob at one segment and I match Mary at another, but when they match each other at a third the two groups will appear to be joined. Most of the time this will be because we are all descended from a CA who passed on all three segments to their descendants in different combinations. This is not always a bad thing, since if I am sure one group descends from a particular CA then the other is linked into that line also.
    3) I match Bob at one segment and I match Mary at another, but they match each other at a third due to a CA who is not related to me. Imagine if one of my paternal cousins married a maternal cousin. Their child would match people on both sides of my tree who really had no ancestors in common.
    The last two problems are more difficult to deal with, but not impossible. In each case there will be two subgroups whose members are highly linked, and then there will be one or two individuals in each subgroup who link to each other and combine the groups. In practice it will be relatively easy to identify these cases. One special case to watch out for is when one administrator has kits in two subgroups- in that case it is almost certain that the link is due to their being close relatives.
    A final point is that Ancestry only reports “In Common With” for 4th cousin or closer. So Bob, Mary, and I may share a segment, but if Bob is a Distant Cousin he will not show up in Mary’s ICW matches, and if they are both Distant Cousins neither will show up in the ICW matches. For now I am including these Distant Cousins and just need to realize that the absence of a ICW match between them is not significant.
    I applied this to my mother’s 15,712 matches. I excluded all of the dyads who just match each other and ended up with 1160 people who match me in one segment and have multiple ICWs. My first attempt gave me about thirty groups. The biggest group has 160 members and has many known relatives descended from Phillip Davis and Margaret Reed. About half of the other groups were also easy to assign to known lines. I haven’t gone to Gedmatch yet to figure out what segment each group corresponds to, but that should be productive.


    • Thanks, Andrew – I blogged on a method to use AncestryDNA, but it included encouraging them to upload to GEDmatch. I found over 50 Matches who all had my 7G grandfather in their Tree. And some of them were in Shared Matches together. But the segment data at GEDmatch showed about 6 of them in one group (on one segment, in one Triangulated Group); 4 of them in another TG; 3 in another TG; and the rest scattered as “onesies”. So your method is a good start – but the real grouping can only be done, IMO, with segment data. NB: I believe AncestryDNA will show a Shared Matches list for every Match; it’s just that the Shared Matches themselves will only be 4C or closer (which really actually includes a lot of true 5C and 6C in their 4C category). Anyway, you can “back into” many more Shared Matches by checking the more distant Matches one-by-one – it’s actually helpful to know this “back door” info and put it in the notes. Jim


      • I read your Ancestry post which is why I posted the above.
        Being aware that Ancestry ICWs cluster into shared segment groups means that you don’t have to contact as many people. If you get a couple of them to post their file on Gedmatch and the segments match you can be reasonably confident that the rest of the group shares the same segment.
        I have several separate groups that each shares a different Davis segment. So, yes, just because a bunch of people are descended from a distant ancestor and are my DNA matches does not mean that they all share the same segment(s) with me or each other.
        I didn’t mention it, but you can also go back and look to see if the people you share multiple segments with are members of the shared segment groups. Since these are closer relatives and presumably easier to find CAs with it can help assign groups to specific lineages.
        Ancestry shows ICWs of 4th cousin or closer for every match. It never shows ICWs of Distant Cousins for any match. So it is fairly common to find a one-way ICW. (Bob is a 4th cousin, Jane is a Distant Cousin. Bob shows up as ICW when viewing Jane’s profile but Jane does not show up when viewing Bob’s.) The DNAGedcom tool is the way to go- a few hours of it cranking away and you have the entire set of ICWs. I don’t have any connection with them- I’m just a satisfied user.
        Anyway, this is yet another complementary strategy. One can never have too many tools in one’s kit.


  6. Although an ICW utility starts with everyone who is already a match (somewhere), the ICW grouping is just built on genealogy – no other DNA input. So an ICW grouping shows groups with the same ancestry, sometimes the link is on different segments. I’ve found this even between sibling Matches. And other times, notwithstanding the ICW group, the DNA linkage turns out to be on a different ancestral line. The ICW groups form good starting points, but there is too much random variation (for me, anyway) to assume they share the same segment. Jim


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