AncestryDNA has rolled out an “auto” Cluster program. I tried it and got 8 Clusters, ranging from 3 to 9 Matches in each one. A total of 40 of my 60 Matches above 65cM. The other 20 Matches were not included because they didn’t form a Cluster of at least 3 Matches. I know the Common Ancestors for each of the 40 Matches and the program clustered them 100% correctly. I’d give AncestryDNA an A+ for this new program. I’m impressed and anxious to have the ability to adjust the cM ranges downward to get more Clusters.

Some additional input on auto-Clustering.

It began in late 2018, with Genetic Affairs (by EJ Blom), and soon we also had Shared Clustering (by Jonathan Brecher) and DNAGedcom Client (by Rob Warthen). I tried all three. I had already done segment Triangulation on all my Matches at FamilyTreeDNA, and I worked with Johathan Brecher and we Clustered those same Matches. There was over 90% concurrence between the hundreds of Clusters and the hundreds of Triangulated Groups. Not enough to say the two processes were equivalent (they are not), but certainly this analysis showed a strong tendency of Clusters to point to a Common Ancestor between me and all the Matches in each Cluster. A very strong clue in each case.

I then Clustered all of my Matches at AncestryDNA – down to about 18cM. Many of the Clusters had a Common Ancestor consensus (easily seen in the Match Notes I had previously entered – many from ThruLines). So, I imputed that Common Ancestor to the rest of the Matches in each Cluster. I used Ahnentafel numbers to represent my Ancestors and developed a tagging code: e.g. #A0020. The #A means a confirmed Common Ancestor with a Match, and 20 is Ahnentafel for William MITCHELL 1824-1895. This code is the first thing in the Notes field. When I impute a Common Ancestor to a Match from a Cluster consensus, I use #L0020 – which means the Match is highly Likely to have that Common Ancestor with me. With a #A or a #L, I tagged almost all my Ancestry Matches over 20cM and many below that. This was in the 2019-21 time frame.

Recently, with ProTools, I’ve been able to determine how many more Matches fit into my Tree – and thus our Common Ancestor. For well over 90% of all these new Match cousins, the #L tag turned out to be correct – I only needed to change the L to A.

Bottom line 1: I am a big fan of Clustering at AncestryDNA and really look forward to expanding the coverage to more Matches.

Bottom line 2: Use ProTools with Clustered Matches to really nail down Common Ancestors to Matches.

[22DI] Segment-ology: A New Cluster on the Block by Jim Bartlett 20250725