31 March 2016

If my genealogy research is solid, how could my DNA results be wrong?

At seminar talks and on her blog, Judy G. Russell, the Legal Genealogist, suggests taking autosomal DNA tests at more than one company because each company presents data in different ways—and, more importantly, you expand your pool of potential cousins. Having tested at FamilyTreeDNA and 23andMe, I decided to follow Judys advice and try AncestryDNA.

And what I found shocked me.

I expected to find an autosomal DNA match with Ruby, my longtime conspirator in tracking down our Gibson ancestors. For 18+ years, weve been email buddies, sharing research and debating potential candidates for our family trees. Our mutual tenacity and our databases proved we were fifth cousins, so why didn't the DNA agree?

Matchmaker, Matchmaker, Find Me a Match

On AncestryDNA, I found cousins from my FamilyTreeDNA and 23andMe match lists, but no Ruby. (She didnt test with the other two companies.) With my 5,000+ hits, youd think one speck of spit would have declared our relationship. But it looked like we were swimming in different pools.

Luckily, AncestryDNA lets us share DNA results even with someone not on our match lists. (From the AncestryDNA home page, click on the Settings button on the right and scroll down to the green button, Invite Others to Access DNA Results.)

After opening AncestryDNA results pages for both of us, I filtered my search for any Gibson born in Massachusetts. We both had four hits, but none of the same. Figures.

This required diving deeper. I checked the family trees of all four of my cousin matches with my genealogy database. Two of them definitely were from my Gibson line, though the other two may be a new Gibson lead or unknown matches with another surname. Then I repeated the same checks with Rubys matches and my database. Her results showed one person shared a direct ancestor with Ruby and me; two had the granddaughter of our direct ancestors; and one matched one of Rubys collateral lines, but the Gibson surname was a red herring.

This case proves Judy Russells other important suggestion: The more relatives you test, the more matches you'll find. Thats because you wont share the same genetic admixture with your nearest and dearest. If possible, have as many close relatives (grandparents, parents, aunts, uncles, siblings, children, etc.) take autosomal DNA tests to spread your nets wider to catch more cousins.

Related Stories:

Some DNA Blogs:

1 comment:

  1. I have a third cousin with whom I have shared a lot of research, and she did show up initially in my Ancestry results - but only with an "Extremely Low Probability." After Ancestry made the threshold for matches much higher, she didn't show up in my results of all. Recombination of DNA often means that you will not share a significant amount of DNA with people who would seem to be close matches.