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… even when they’re frustrating

The Legal Genealogist owes readers an apology.

Between the June week of the Genealogical Research Institute of Pittsburgh (GRIP) and a hard-to-diagnose technical issue with the website, the blog has been really quiet this week.

And it may not get a whole lot better for a while as the July GRIP is coming up fast, and the Midwest African American Genealogy Institute the same week, and then the Institute of Genealogy and Historical Research, and…

You get the picture.

But I did take a break for a short time and play a little with my own genealogical DNA results yesterday, just to see how the numbers stack up with even the limited support we can get from Ancestry’s ThruLines.

We all have 64 fourth great grandparents and 128 fifth great grandparents. If cousins married cousins, those numbers can change a bit in what’s called pedigree collapse.1 But I don’t have any known pedigree collapse that close (I have a set of fifth great grandparents who are also my sixth great grandparents so I start to lose unique individuals from my tree at that level), and that makes the fifth great grandparents a good level to look at.

So… remember how ThruLines works. It takes our trees and the trees of our known DNA matches and suggests the likely common ancestors. If the trees are wrong, the suggested common ancestors will be wrong. And even if the trees are right, ThruLines won’t account for DNA that may come down from another as-yet-unknown common ancestor who isn’t in one or both of the trees.2

All that being said, it still highlights the one reality of my ancestry: I have some lines that have a lot of genealogists (or at least a lot of DNA testers), some lines with darned few, and — sigh — the Germans still aren’t testing in high enough numbers to help out at all. Oh, and an awful lot of people who — like me — have no clue who the MRCA is in a particular line.

ThruLines screen capture

The lines with an abundance of testers? All from the U.S. southern states:

• In my Baker-Davenport line (Virginia to North Carolina), more than 100 matches even excluding those who are my close kin (sister, cousins, aunt and uncle).

• In my Wiseman-Davenport line (Virginia to North Carolina), more than 130 excluding close kin.

• In my Buchanan-Boswell line (Maryland to Virginia to North Carolina), more than 180 excluding close kin.

• And in my Jones-Pettypool line (yeah, you got it: Virginia to North Carolina), we’re pushing close to 300 matches.

And yes — sigh — the Bakers married the Davenports married the Buchanans married the Joneses, all in western North Carolina.

The lines with the fewest testers? The Germans, by a long shot. I have at least some documentation for 28 German fifth great grandparents. For 17 of them, I have exactly one match: my sister. For one more, my matches are my sister and my niece (who should match me on the others but hasn’t added them to her tree). For another eight, I have two matches: my sister and a fourth cousin, whose second great grandparents emigrated to the United States in the 1850s. We have, of course, no matches in common since you don’t get shared matches on Ancestry if you don’t share at least 20cM of DNA in common, and I only share one 8cM segment with this fourth cousin.

And for the remaining two German fifth great grandparents, I have three matches besides my sister: a possible fourth cousin once removed whose almost entirely undocumented tree shows a shared ancestor married to two different men with the same surname both born in the same year, and a possible fifth cousin once removed and a possible sixth cousin — whose trees show a second German surname that could just as easily explain the match in Germany. Oh, and yeah… and who have a Baker ancestor in colonial Virginia.


Of course that’s still better than the ThruLines showing that Matthew Johnson, my third great grandfather in another out-of-Virginia line, could be the son of at least two different guys. Like John Joseph Daniel Johnson based on (for example) a tree where (a) the sole source is (yep!) other undocumented Ancestry Family Trees and (b) the Matthew Johnson shown and all his siblings were born in North or South Carolina rather than Virginia and (c) that Matthew died in 1887 in Georgia — whereas mine died about 1863 in Kentucky.

But hey… it’s a hint, right?

Now… despite my frustrations, let me make it clear: these can be valuable hints. They can still do a lot to help put families back together. I noted today, for the first time, a tester who descends from a second great granduncle who died in Iowa in the 1850s where we share a whopping big 42cM segment.

So even when — in moments of frustration — I think I may be through with ThruLines, in fact I know I never will be. Not when they can put me in touch with cousins like that.

How are your ThruLines helping… or not?

Cite/link to this post: Judy G. Russell, “Not through with ThruLines,” The Legal Genealogist ( : posted 26 June 2022).


  1. See e.g. DiAnn Iamarino, “3 Ways to Find Double Ancestors in Your Family Tree,” Family Tree Advice, posted 16 Aug 2019 ( : accessed 26 June 2022).
  2. See “AncestryDNA® ThruLines®,” AncestrySupport, ( : accessed 26 June 2022).
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