Tuesday, December 25, 2012

With DNA the known connection may not be the genetic connection

Neither of my parents are alive. All of my Father's siblings have passed and only his half-sister has descendants. Two of my Mother's siblings are alive but neither one has tested. I had 11 first cousins, one is deceased, 2 being related on both my paternal and maternal sides, 2 being descendants of my paternal grand mother through her first husband, and 8 being descendants only through my Mother's siblings. So far I have tested two of them, a 1st cousin from both lines (A) and a 1st cousin only through my Mother's side (B).

At 23andme I have three matches with a 5th cousin (C) who descends from from a couple on my Father's side. This is on one of my paternal great grandfather's line, one of the lines neither of my tested 1st cousins shares with me. Her maternal ancestry has several names in it that are in my maternal ancestry, but they are not traced back to a common ancestor. However, her mother has connections to a county in Arkansas where many of my relatives settled between 1830 and 1860.

When I compare her results to my two first cousins in Family Inheritance: Advanced She has matches with (B). Since (B) is my first cousin through her father, my Mother's brother, and her Mother was from a county that is not in my ancestry nor in (C)'s ancestry, the genetic relationship appears to actually be from (C)'s Mother's side and not from her direct paternal ancestry where she and I have the documented paper match.

This points out two concerns: the paper link is not necessarily the genetic link; and you need to have some way of determining which side of you ancestry the genetic link is on; either full phasing by parent-child groups or by testing your parent's siblings or your grandparents, or selected close relatives, like first cousins, as was done here.

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