Wednesday, March 6, 2019

Can AncestryDNA's ThruLines Find Cousins From Potential Ancestors?

Like many genealogists, I have several "brick walls" in my pedigree chart.  No matter what resources I look for, I can'rt seem to find parents for several of my 2nd and 3rd great-grandparents.  

One example is my 3rd great-grandfather, Thomas J. Newton (about 1800 - about 1850), who married Sophia (Buck) Brigham (1797-1882) in about 1834, and had my 2nd great-grandmother, Sophia (Newton) Hildreth (1834-1923).  

I noted earlier that the new AncestryDNA  ThruLines feature suggested "Potential Ancestors" in the ThruLines main page, as shown below for potential parents of my Thomas J. Newton: 

In my genealogy research, Jacob and Fanny (Park) Newton are candidates to be parents of my Thomas J. Newton, although their son Thomas J. Newton (1808-1852).  However, I have found no evidence that this is my Thomas J. Newton person. This Thomas and my Thomas were both born in Maine and lived in eastern Massachusetts in the 1830-1850 time frame, so it is possible.

If Thomas J. Newton (1808-1852) is my 3rd great-grandfather, Jacob and Fanny (Park) Newton would be my 4th great-grandparents, which would make 5th cousins in my generation  a possible DNA match with me.   I clicked on the link for Jacob Newton and saw:

Well, there are no other DNA cousins except the ones in my known line (my first and second Seaver cousins).

But wait, the ThruLines goes down to 5th great-grandparents, and ThruLines also listed as "potential ancestors" the parents of Jacob Newton - Levi Newton and Sarah Woodward.  I clicked on Levi Newton's link and saw:

Aha!  There is a 6th cousin with 6 cM in 1 segment who is listed with a defined Newton line.  Of course, 6 cM is really small, but is possbile for 6th cousins who are a known match (the Bettinger Shared cM project lists 21 cM as the average of known relationships, with a range is 0 to 86 cM).

Before I ignore this lead, I have to remember that this may be a real DNA match, and if I am not related to this DNA Match on this Newton line, then I may be a cousin on another ancestral line that is not in the Ancestry BIG Tree.

I also checked for Fanny Park's parents as "Potential Ancestors" and they were not on the ThruLines list.

So this may or may not be a real relationship - I can't know for sure without more information.  But it gave me pause to consider it.

I am a bit leery of the Ancestry ThruLines because it is derived from the Ancestry BIG Tree, which combined millions of Ancestry Member Trees into one big tree of over 800 million profiles several years ago.  When relationships differed between trees (e.g., one tree indicated that Thomas Newton had parents Jacob and Fanny (Parks) Newton, another tree may have indicated Nathan and Dorothy (Wood) Newton) and Ancestry chose one of the selections based on unknown criteria.

As for the question posed in the blog post title, the answer is:  YES, AncestryDNA ThruLines can find cousins from Potential Ancestors.  But, and it's a big one, the DNA Match found may be a result of some other ancestral line.


Copyright (c) 2019, Randall J. Seaver

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Gayle said...

Hi Randy. First time to comment. Thank you for your well researched blog.
You've expressed the same reservations I have had for a long time concerning unknown lines and shared matches. Using the DNA test provides some leads but not all answers.

Marian B. Wood said...

Very good points. Like you, I'm taking these "potential ancestors" and their descendants one at a time and investigating carefully to be sure before I do anything with these hints.

Kim said...

I note that I am given a potential ancestor when my family tree has a well defined ancestor. The potential ancestor is definitely wrong. So far I have not found a method of eliminating the potential ancestor and having my well researched ancestor appear.