Matching unmatched DNA matches by Casting a Wide Net, Part 4 – Proving the matches, and establishing a theory of connection

Matching unmatched DNA matches by Casting a Wide Net, Part 4 – Proving the matches, and establishing a theory of connection

In the first three parts of this series (Part 1, Part 2, Part 3), we went through and tagged all 288 of our Ancestry DNA results that were related to a group of matches which had Woodley/Woodson surnames in their attached trees. We then built out a common tree for as many of the matches as we could, to nail down common ancestors, and to gain clues on where these matches link up with our tree. In this installment, we leverage GEDmatch, and deductive reasoning, to identify where we think our tree will link up with their trees.

The largest DNA matches (by centimorgans) we identified in Ancestry had also uploaded their DNA results to GEDmatch, so we were able to do tests to confirm they all truly matched. The “One-to-One” matches for each of them confirmed they were all related to “Mary”. It’s not scientific to say that all 288 were actual DNA matches, but we know the core group of matches are and that a good number of the matches-of-matches are likely also legit.

X DNA is tricky, but the important use of it identifying people who you CAN’T be a match if you share X DNA.

We were also able to use GEDmatch to identify the “true” cM match amounts between various matches, and from there we leveraged the International Society of Genetic Genealogists’ table showing cM ranges and averages between various family relationships (Shared cM Project – V3). The closest match for Mary was “W.W.”, and we settled on 133cM as their match level. The most likely relationship for that level of match was with a shared Great Grandparent, with W.W. likely being a 2nd Cousin, or a 2nd Cousin Once Removed. When we fleshed out the other 12 matches on paper, they all roughly fit this notion that they matched either Mary’s Great Grandparent or Great-Great Grandparent.

female-x-chart
Inheritance pattern for females (X DNA)

The other thing that jumped out at us, unexpectedly, from GEDmatch was that some of the 5 matches there had X DNA matches as well. X DNA is tricky, but the important use of it identifying people who you CAN’T be a match if you share X DNA. For example, a person will only inherit X DNA from their mother, so if you have an X DNA match that you’re theorizing is related to someone, but there are two male relatives in a row between the two matches, that isn’t possible.

Once we built out the theoretical map between all the matches and Mary it all fit that her GGP’s could be Roman and Mary Jones, and with the DNA levels and inheritance pattern of X DNA it’s likely that Marie’s relative was a daughter of Roman and Mary. It also pointed strongly to the matching being on her mother’s side.

 

Screen Shot 2018-08-10 at 3.18.43 PM
“What are the Odds?” gives you the chances of various hypothesis’

The day after we did our work on paper with the ISOGG chart as our guidance, DNAPainter introduced a new tool called “What are the Odds?”  that does the same work we just did on paper! It’s easy, it’s awesome, and we’ll cover it in more detail in a future post. But, most importantly, it showed us that it was 77 times MORE likely that Roman or Mary Jones’s parents are our Most Recent Common Ancestor, than anyone else. It’s technically possible that our Mary is directly descended from Roman and Mary Jones, or that they are connected by 4xGGP’s…but it’s much, much more likely we’re looking for Mary’s 3xGGP’s, the parents of Roman and Mary.

Looking at Mary’s tree, and she of course has 2 maternal GGM’s. One, we have some documentation (mostly Census info with Ancestry Member Trees), but the other we had almost no information. We’re guessing the one we have little information on, Annie Caswell, might be the best lead, so we’re going to dig into her.

Samuel and Annie Caswell were born, married, and died in and around Crowder, MS. Family lore has Sam and Annie as Mary’s grandparents, but we only have Annie’s Census birth date, and no maiden name for her. About the only piece of hard information we had was that Samuel might have died in July 1974 (based on the SSDI).

Time for some old-school genealogy, to hopefully prove out the high-tech theory that points to Annie Caswell being on the Jones line.

Next in the Series: Matching unmatched DNA matches by Casting a Wide Net, Part 5 – Rolling up our sleeves and doing some genealogy

3 thoughts on “Matching unmatched DNA matches by Casting a Wide Net, Part 4 – Proving the matches, and establishing a theory of connection

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