Ways to analyze Shared Matches Of Matches (SMOM) cMs.

Pro Tools gives us a LOT of new information. Not quite segment Triangulation, but very powerful data.

For example a Match shares 8cM with me and does not have a Tree. However, a SMOM shares 3,489cM with the Match, and Ancestry (with insider info) says the SMOM is the mother of the Match; and shares 17cM with me. As it turns out, I know the SMOM is a 3C1R with me on a particular Ancestor couple. It’s easy to 1. add the Match to my Tree; 2 add the Match to my Common Ancestor Spreadsheet; and 3. add a synopsis of this info (as a 3C2R) to the Match’s Notes. Of course this doesn’t happen every time, but it does happen some of the time.

The above example is a parent/child relationship, and Ancestry usually knows if it’s a son or daughter and a mother or father. Ancestry usually knows niece/nephew and aunt/uncle.

But the thrust of this blog post is about a family group and their interrelationships.  I’ve tried several methods to document and analyze new Match/SMOM cMs. All methods utilize my Common Ancestor Spreadsheet which is arranged by family groups [I sort by Ahnentafel of the Common Ancestor; and the birth years of children, grandchildren and great grandchildren.] This CA spreadsheet is my foundation of “known” cousins – I’m looking at their Shared Matches to see if I can determine how we are related and add them to the spreadsheet; and checking to see that the existing cousins are interrelated to each other as expected.

First try was to add about 10 blank columns to the spreadsheet. I’d then type an asterisk [*] for a Match in a column, and enter the shared cMs with the other Matches in the spreadsheet in the same column. It was sort of like a Cluster matrix; and anyone who had a faulty genealogy was easily highlighted. But two issues: 1. It was a lot of work for a family group; 2. some of the Matches were in fact related up or down a generation [not physically close on the spreadsheet]; and 3. it was difficult (for me, anyway) to determine how an unknown Match would fit in… [someday I’ll try DNA Painter or BanyanDNA…]

The second try was just one new column, and I would type in the highest cM found among all the Shared Matches; the suggested relationship [almost always accurate for high cMs];  the Match name; and any known info. Issues: again, a lot of work; and some Matches don’t have any high cM SMOM with me.  I still add these when they are the only evidence I have for adding a new Match to my Common Ancestor spreadsheet.

Third/current try involves about 3 new columns and I color in a column where Matches match most of the others. Sort of like LEEDs column-coloring. This is somewhat easier to do, without a lot of typing. And the colored “stripes” are comforting to see (and to highlight Matches who may not “belong” and/or need further research.)

Also, I’m hopping around some these days, working on specific issues (Brick Walls, questionable genealogy, trying to link in (or out) selected Matches). It appears that the closer generations have one stripy column and as I work on more distant Ancestors, the number of colored columns grows.

I’m still fiddling with good/efficient ways to use/display SMOM cMs; or even if I need to at all. I’ve worked on about 10% of my Matches in the Common Ancestor Spreadsheet. At every turn, Pro Tools is helping me find more and more Matches for whom I can determine our relationship. So still a long way to go – and I’m sure there are many more Matches to add to my spreadsheet.

You are encouraged to post in the comments any insights, tricks or hacks you’ve developed for using SMOM cMs…

[22CS] Segment-ology: Pro Tools 11 – Ways to Analyze SMOM cMs by Jim Bartlett 20241027