Friday, April 21, 2017

Skeletons in My Closet, Part 3

Autosomal DNA tests came in for the three sisters a couple of weeks ago and I have been comparing them with some of the kits on my maternal side of the family.

Below is a chart of the total shared cM between the three sisters (D, M, and S), my mom, my two aunts, my uncle, my brother (actually my half-brother), my sister, and me, obtained from Family Finder Matches at Family Tree DNA.

This is another chart of the matches obtained from the GEDmatch 3D Chromosome Browser using the cM threshold of 5.

Based on Blaine Bettinger’s The Shared CM Project, for a first cousin relationship with the sisters, my brother, sister, and myself should have around 533-1379 of shared cM. For a relationship of aunt/uncle with the sisters, my mom, aunts, and uncle should have about 1301-2193 of shared cM.

Remember, we are also related through my maternal grandmother. Just using that side of the family, my brother, sister, and myself are second cousins, once-removed to the sisters and should share around 0-325 cM. My mom, aunts, and uncle are second cousins to the sisters and should share about 43-504 cM.

If my brother, my sister, and I are half-first cousins to the three sisters (sharing the same grandfather but different grandmothers), we should share an average of 425 cM according to the table located at the International Society of Genetic Genealogy Wiki page. My mom, aunts, and uncle should have about 850 cM shared since they are half-aunts and half-uncle. It looks like we have met that requirement.

I also performed the “In Common With” feature on everyone at Family Tree DNA and used various lines of my grandfather (O’Rear, Humphries, Harbison, Alexander, Cole, Kinney, Henderson, Stephens, and Gann). This would have been easier if more matches would have had ancestral surnames and/or GEDCOMs associated with their kits.

This project would have been more difficult if I did not have a clue about the paternal grandfather of the sisters. I would have most likely have used some additional third-party tools.

What’s next? I am testing four more of my maternal first cousins in a couple of weeks. I am also going to research the maternal lines of the sisters to help sort out all of my maternal lines. Their father also had three siblings with unknown fathers so I will see where that will lead. Personally, I am going to start to work on assigning chromosome segments to my specific ancestors. I have more mysteries to solve!

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