The Genetic Gods Were Smiling

Last week the genetic gods must have been smiling on bloggers -- at least a couple of us. Judy Russell reported in her The Legal Genealogist blog that she had discovered her first "known relationship" through 23andMe. 

At about the same time I experienced my easiest "known relationship" find there. In this case it was not a match with me but a match between my daughter-in-law and a male predicted to be a:

2nd Cousin 3.57% shared, 12 segments

As you may know a match of this size is consistent with a second cousin match but it is also consistent with a first cousin -- twice removed. 

Those of you bucking for an “A” in genetics this semester may have already noticed one important thing about the matches shown below that made this genealogy mystery much easier to solve:

There is a significant match on chromosome X. Why is that significant some of you may ask? If you were paying attention above, I told you that the unknown potential second cousin was male. That means he inherited his entire X chromosome from his mother. Therefore, his match with my daughter-in-law must be on his mother's side of his family tree. This cuts in half the number of branches of his tree we had to consider.

It did not reduce the amount of my daughter-in-law's tree we had to examine. She had inherited one X chromosome from her mother; but she had also inherited one from her father as well. So I sent a list of her 8 great-grandparents to the wife of her match who was the family genealogist. The wife responded, "It's Homer and Hilda". Mystery solved!

His mother and the mother of my daughter-in-law are 1st cousins. I've had a few other successes at 23andMe but none this easy to achieve.