10 years ago, I blogged: “What is a segment?”, and noted the difference between an ancestral segment (your DNA segment) – passed down from an Ancestor to you; and a shared segment (created by a computer algorithm) which usually indicates a Common Ancestor for both you and your Match.
This is still the fundamental concept that is key to genetic genealogy.
We’ve looked at a lot of twists and turns based on this concept…
– How segments are measured
– Why the data is a little fuzzy, but that doesn’t negate its power
– How our DNA is passed down in identifiable segments from our Ancestors
– How each generation of our Ancestors contributes two full genomes (46 Chr) to us
– Why some of our segments must be sticky (persistent) for multiple generations
– How we “see” our own segments through shared segments
– How we can map (or paint) our segments on our chromosomes
– How shared segment “size” predicts relationships
– How we can group Matches by segment Triangulation or shared Match Clusters
– How we can use groups to solve brick walls, NPEs, Bio-Ancestors, unknowns
– Which ancestors always, or sometimes, or never have shared Matches
– Why all of our shared segments (6cM and up) may be important to us
– How to Walk Ancestors, Clusters, Segments back in our genealogy
– How spreadsheets can help us collect, arrange, analyze, QC, and use data
– How to use new tools: autoClustering, DNA Painter, browsers, ProTools, etc.
You have all been part of this journey of learning – as in fact, we are all learning from each other. I very much value your feedback and suggestions.
As some of you know, I also host DNA Special Interest Group (SIG), through the Washington DC Family Search Center. It was in person/local until Covid. We are now international via Zoom – 2nd Wednesday of each month 7-9pm ET. This is now an Advanced DNA SIG, and members are encouraged to participate and/or present (learn from each other). If you’d like to join, please email me at jim4bartletts@verizon.net
Happy Anniversary – your suggestions/observations/comments are “gifts” to us all.
[99F] Segment-ology: Happy 10th Anniversary by Jim Bartlett 20250507
segment-ology 
Congrats on 10 successful years, Jim! I’m a newbie to your blog and feel very honored to be here. I look forward learning all I can from you for 10 more years and beyond!
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Congratulations, Jim, on the 10 year anniversary of Segmentology. It is a gold mine of information, which I’ve referred to time & time again. Thank you so much.Andy Howell
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Thanks, Andy – It’s made me think hard about how the DNA works, Jim
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Congratulations Jim and thanks for sharing all these years, you’ve helped us all learn a lot. I’ve been a fan since the beginning too! We actually first connected in 2012 as DNA matches, sadly we worked out after a few years it was one of those pesky false matches!
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Veronica, Thanks for staying with me, even tho we missed out being genetic cousins… Jim
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Congratulations on 10 years Jim! Your posts have both educated and inspired me me to dig deeper into my genetic genealogy. Anytime I see a post on Ancestry asking about segments, I send them to those early posts of yours. They have always been the most logical and simple (mostly!) way of understanding a complex and at times confusing subject. Here’s to 10 more!
Pat
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Pat, Thanks for you knid feedback. It’s been a hoot – and I’ve got a backlog of thought and insights still in the hopper. Jim
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Congratulations on your anniversary! I’ve learned a lot from your posts. Have you thought about putting them into some kind of archive if you decide to stop doing genetic genealogy?
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Cheerful, Thanks for your “cheerful” feedback. And, to your question: YES – stay tuned… Jim
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Congratulations Jim! You are awesome and smart and I really appreciate the last ten years reading and trying to learn from you. Thanks so much.
Karen
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Hi Jim,
Congratulations! I remember that first blog and the early days of A-DNA genealogy tools. At that time I had been working pretty intensively with Y-DNA and was fortunate in discovering a SNP, dated about 1600 by FTDNA, that I uniquely share with another Manx Morrison who now lives in Australia. With the goal of tracing our roots back to this MRCA, I then delved into A-DNA, learning mainly from your “Segmentology” blogs and using GEDmatch tools to trace my Manx cousins back to the early 1700s. I was able to dig even deeper using the original probate court and land records held by the Isle of Man Museum and was finally rewarded in identifying our probable MRCA — William McYlvorrey (the Manx Gaelic cognate of Morrison) — who died in 1648.
Of course, we have discovered many cousins along the way and I have found wonderful friendships with some of my distant Manx relations in IOM and throughout North America. Thanks, Jim, for your part in making this possible.
Gary Morrison Victoria, BC
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Gary, Thanks for the feedback and your longtime involvement. We were, and still are, learing from each other. Thank you. Jim PS: I hope you know my friend Mark Thompson, also of Victoria – GO CANADA!
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congratulations on your anniversary and thank you for sharing your insights over the last decade
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