BLUF*: Unknown Clusters do NOT “fit” where known Clusters fit. Try using geography or ethnicity to find a fit.

Clusters form on a Common Ancestor (usually a couple). We can form Clusters by hand by grouping shared Matches who match each other. We can use automated programs at MyHeritage, GEDmatch, Genetic Affairs, DNAGedcom Client. These auto-programs generally Cluster all Matches within a given range of cMs – say all above 60cM. Important: they will produce Clusters across your Ancestors, whether you know those Ancestors or not. Clustering does not depend on genealogy. Matches without Trees are Clustered just as easily as Matches with full Trees.

So think about the implications…  say we did an auto-run at My Heritage and got 22 Clusters. The Cluster programs cannot give us a set of Clusters from just one generation – so we would expect to be a range. In a perfect world, 16 Cluster would align with our 16 2xG grandparents which show up as 16 3xG grandparent couples. This doesn’t happen… In my experience I’ve found that 22 Clusters would shake out over a range of generations – say roughly as 2 2xG grandparent couples; 12 3xG couples; 6 4xG couples ; and 2 5xG couples. The mix gets wider/wilder as we drop the cM threshold and the number of Clusters increases. The main point here is that there will be a distribution over several generations.

Another observation is that, in general, no two Clusters will form on the same ancestral couple. Also, we find some Matches may have a relationship to more than one Cluster (as usually shown with “gray” cells in the full Cluster diagram).

So, suppose I have 22 Clusters, and “know” which ancestor couple goes with 19 of them. What about the other 3 Clusters? Maybe the Matches don’t provide enough information for me to assign the Cluster to a Common Ancestor. Maybe the Matches provide a lot of Tree information, but none matches my Tree. I have to stop and think!

I don’t know the Common Ancestor couple (CA) for these 3 Clusters. However, almost certainly, I can rule out the 19 known CAs. Circle these in my Tree! Now look at the pattern and the “bare” spots. It’s highly likely that the 3 unknown Clusters will “fit” into the bare spots. Use judgment. Also use two other clues: geography and ethnicity. See if you can tease these clues out of the Matches in each Cluster. Compare to the best knowledge of your Ancestors in the bare spots of the likely generation in your Tree.   

Summary. Unknown Clusters point to one of your Ancestor couples, just as accurately as the “known” Clusters did; it’s just that there is not enough genealogy to “make the call”.  See if other information, like geography or ethnicity, can help.

Please post in the comments section if you’ve found other ways to link Clusters to CAs.

 *Bottom Line Up Front

[22DP] Segment-ology: Where Do Clusters Fit; by Jim Bartlett 20260828

This is about working with relatively distant Ancestors with a big generation gap back to their birth year. I’m talking about what I call my 567 Ancestors – 5XGreat grandparent; 6C level; 7 generations back. We each have 128 of these Ancestors. Because they are at the 6C level, they are fair game for ThruLines. But because of my age (83), most of my cousins are 6C1R or 6C2R or 6C3R – all “out of range” for ThruLines. The generation gap is too large for them…

Current case in point – my newly found 567 Ancestor: Ahnentafel 196 > James BROWN who wrote a Will in 1776 in Cumberland Co, VA naming 16 children. For some reason this Will was not well known until recently, and many folks had already found other “likely” Ancestors to build out their Tree . This makes it all the harder to find the correct links and “pry” those lines away from the wrong Ancestors. We estimate James was born c1720 – roughly 300 years ago – and, sure enough, almost all my Matches back to James are “removed” from 6C and out of reach for ThruLines. Living Matches are usually 8, 9 or 10 generations down from James.

In this case the “hack” of linking my DNA to my mother, or her father, does not work – it shortens my path, but does not shorten the path for my Matches.  Personally searching for my Ancestor; building back Trees for shared Matches; etc.; is labor intensive. AND I cannot “see” into Private (searchable) Trees like ThruLines can. And ThruLines has the patience to “build back” Match Trees and find the links – and quickly, too.

Subtitle for this blogpost – Make ThruLines Work for You.  

So, shorten the path for your 6C2R Matches. I created 3 dummy Ancestors to connect from my mother to a known *grandchild of James* (which grandchild would be 567 (ie 6C level) for my 6C2R Matches (even closer for my 6C1R and 6C Matches).  I disconnected my mother from her father and instead typed in Grand Father and used my grandfather’s birth year. Then for his father, I typed in Great Grandfather with realistic birth year. Then for the next generation, I typed in 2Great Grandfather and a birth year and then linked him as a child the grandson of James. Note: ThruLInes looks at “boxes” and “links”, not names.
This made it look like the *grandson of James* was my 3xG grandparent (4C level). Now, I and my 6C2R Matches were within the range of ThruLines. Wait about 4 hours and ThruLines gave me 58 Matches!! Like most of my ThruLines they turned out to be 90-95% correct. In 4 hours! Talk about drinking through a fire hose…

Once I had the Match names and paths, I could easily add them to my Common Ancestor Spreadsheet. Then call up each Match and do some “housekeeping” 1. do genealogy diligence checking; 2. Use ProTools to find other close shared Matches ThruLines didn’t pick up; 3. Check for close Matches with UnLinked Trees which ThruLines ignores (some are good, some not) – my current cutoff in a shared Match list is about 90cM to the Match.

My request is that if you use this method, please give the dummy Ancestors names that won’t mislead others looking at your Tree. Maybe for names use GP, GGP, GGGP as first names and DONOTCOPY as last names. And, of course, as soon as you’ve recorded the info you want, restore the true Ancestor link on your side; and remove the link at the top end. This will leave these three “dummy” Ancestors as a floater, which can then be easily used elsewhere between your parent and the child or grandchild of a Match. This could also be used for your 678 Ancestors (7C level)…

Adding a rough picture showing the 6C2R problem and the 4C2R fix that ThruLines can work with:

If you try this, please feel free to report back here in the comments. Improvements in method or description are desired. Or a reinforcing: “it works”….

[22DO] Segment-ology: Mind The Gap; by Jim Bartlett 20260820