Shared Match Cluster Hints

I’ve written in this Pro Tools series about the power of Shared Matches. They form manual Clusters of Matches. Like all Clusters, they *tend* to point to a Common Ancestor. Each individual Match has their own ancestry, and they may relate to us in several different ways (particularly with my Colonial Virginia ancestry). With auto-Clustering this is displayed by placing the Match in a Cluster with the strongest ties to other Shared Matches – and using gray-cells to indicate ties to other Clusters. This shows up in a Shared Match list with a mix of Shared Matches tied to one Common Ancestor, along with other Shared Matches who may be related in different ways, and even some Shared Matches who might not be interrelated at all.

So, to make a point: Shared Match Clusters (or concentrations in Shared Match Lists) should be considered as a Hint. The stronger the consensus, the stronger the Hint. The chore that still remains is tracing the genealogy from the Match to a Common Ancestor(s).

I find that consensus is a judgment call. But when I make that call, I usually find other Matches with a genealogy link as expected. But not always…

Segment Triangulation is fairly precise – each of our DNA segments came to us from one particular ancestral path. Shared Matches (aka In Common With, aka Relatives in Common, etc) are not equivalent to Triangulation. When Shared Matches form a Cluster, it’s a strong Hint. And a 20×20 Cluster is much stronger than a 3×3 Cluster. And a 20×20 Cluster where each Match matches almost all of the other Matches is very strong, compared to a 20×20 Cluster where each Match only matches, say, half of the others… I have found large, strong Clusters (beyond close cousins) usually turn out to include one TG (maybe two), but there is no hard rule.

Summary: Shared Matches can grouped into Clusters. Clusters are not the same as Triangulated Groups (TGs), but they can be good pointers and helpful Hints.

[22CW] Segment-ology: Pro Tools Part 15: Shared Match Cluster Hints by Jim Bartlett 20241125

Jigsaw Puzzles

Our genetic genealogy is very much like a jigsaw puzzle. Our Ancestors and our DNA segments are both pieces of a large jigsaw picture (ourselves). Soon after the moment of conception – when sperm meets egg – our DNA segments and crossover points are determined. And, of course, our Ancestors, each with 2 biological parents, are determined. There may be lots we don’t know, but those configurations (DNA and Ancestors) are fixed – waiting for us to discover them. Just like a box of jigsaw puzzle pieces, all the pieces  are there – and they only go together one way (like our DNA segments and our  Ancestors).

Now think about our DNA Matches – perhaps 100,000 of them – as we open our list…   The overarching concept is that a Match sharing at least 15cM with us is always a true (Identical By Descent or IBD) relative; and over half of the remaining Matches will also be IBD and a true relative. Of course, some of these Match-relatives will be distant cousins.

Based on my deep dive with Pro Tools, I’m now convinced at least 20% of my DNA Matches at Ancestry are relatives within a genealogy time-frame. I’ll go out on a limb and say 8C or closer!.

So, to the point of this blog post… 20,000 of my 100,000 Matches are probably 8C or closer. Each one of them is a jigsaw puzzle piece. Each one interlocks with me (sometimes in multiple ways) and very often with other Matches (look at *their* Shared Match list). In many cases they form interlocking relationships with each other, from siblings to parent/child to 1C and 2C and 3C interrelationships. Just like a jigsaw puzzle. Some will be like the jigsaw lake, or forest, or barn or road – all of which “clumps” of the puzzle will eventually integrate – only one way – into the grand picture….

With Pro Tools’ new Sort feature (the Shared Matches’ *close to distant* Sort), it’s a whole lot easier to form small branches. Think of it this way…. You have 1,000 Matches, and you can easily find links that result in 500 pairs….  In a flash, you’ve cut your workload in half. And as you form larger clumps of Matches – all of your Matches in that clump must lead back to you! Put another way, look at the clump and see where all of your Matches have a Common Ancestral line – out of the clump and directly into your Tree – somehow…

The jigsaw puzzles:

1. The Ancestors must interlock in pairs and form an entire “Tree” jigsaw picture>
2. The DNA segments must array adjacently and form a Chromosome Map picture
3. Our Matches will interlock with us; each other; and our Ancestor Tree.

[22CV] Segment-ology: Pro Tools Part 14: Jigsaw Puzzles by Jim Bartlett 20241124

Status of Common Ancestor Spreadsheet

I have a spreadsheet of all Matches with Common Ancestors with me. It includes my Ancestors and their children down to each Match. See more at https://segmentology.org/2021/12/19/segmentology-common-ancestor-spreadsheet/ It’s a lot of work, so feel free to adapt it suit your needs.  

I have been reviewing all of these Matches and adding a LOT more using Pro Tools. I posted various ways to do this here, and I’ve gone down all those rabbit holes. I’m now on a march to review these Matches methodically – from closest Ancestors to more distant. I’ve found that it’s essential to have “known” Matches highlighted in Shared Match lists to speed the process of determining new Matches with CAs and forming family groups. So I’m adopting a two phase process. First: Recheck all Matches for firm relationships and having a clear set of Dots that will spotlight them in a Shared Match List – probably out to 5C level; Then: I’ll go back and use Pro Tools to tease out new Matches to add in.

Toward this end, I’m going to paste a Table below that shows my progress to date; and later I’ll update the Table to show the effect of Pro Tools. I’ve used Ahnentafel numbers (male of an ancestral couple) – their names are not needed for this exercise, although I did use given names for children for the first two generations. The comment column gives some reasons why the cMs deviate from the averages as when there are double Cousins or half Cousins, or Ancestors out of the US. You may also note the high number of Matches for Ahnentafel 70 – it’s because I jumped to that Ancestor, and used Pro Tools to find several key Matches to help with a burning question.

Here is where I stand now:

Note that this summary has 2477 Matches, through the 5C level (4XG grandparents). I have another 6,070 Matches in the 6C to 8C group.  My total is 8,547 Matches from AncestryDNA, out of about 100,000 total – I wanted to see what impact Pro Tools will have. We’ll see how far I can get…

[22CU] Segment-ology: Pro Tools Part 13 – Status of Common Ancestor Spreadsheet  by Jim Bartlett 20241117