Establishing my Great-Grandparents DNA Profile

Well, parts of it anyway. 🙂

This week, the 23andMe DNA Roots Into the Future results came back for one of my mother’s paternal 1st cousins.  A great advantage of her having done the test is that I can now begin to establish segments of my mother’s DNA that comes from her paternal grandparents,  Lewis & Lucinda (Lennon) Robinson, whom Cousin C and my mother have as their Most Recent Common Ancestor (MRCA).

“Cousin C” shares 10.5% and 28 segments of DNA with my mother.  All 28 of those segments come from Lewis & Lucinda.  Additionally, Cousin C shares some DNA segments with my mother’s brother that she does not have in common with my mother (11.2% and 32 segments).    Because the sharing with my mother and uncle are not 100% overlapping, this means even more segments from the great-grandparental units.

In the image below the DNA Cousin C shares with my mother is marked with green; the DNA she shares with my uncle is marked in blue.

This means that as I sort through my mother’s Relative Finder matches, if someone matches both her and Cousin C – then that person is related to us through Lewis & Lucinda and will thus help me narrow which branch to focus the search on.  As I have started to tabulate these shared segments into my analysis spreadsheet I have already identified a few individuals who I can now narrow our search for our MRCA to that branch of my tree.

And also of interest, I have parts of DNA of a set of my 2nd great-grandparents, Andrew & Gracy (Bullock) McNair on my mother’s side since a 3rd cousin of hers, for whom Andrew & Gracy are the MRCA, has also had his testing completed.  On my father’s side, I’ve got DNA segments attributed to ancestors of mine even more generations back that these — how cool is that?

I really need for one of the DNA testing companies to add the tagging capability I’ve described on my blog in the past — it would be so helpful!

Comments (5)

  1. Melvin C.

    Wow! This is so cool! I wished I had been diligent in getting more family members to take the free test.

  2. taneya (Post author)

    Melvin – I have learned SO MUCH from getting extended family members tested. And, I still have several more to go. The ability to map out DNA sequences to across several branches of my family has been phenomenal. It is my hope that over the next few years the cost of the kits continue to decline. A price decrease would make it easier for me to purchase kits in the future for even more family members. Thanks!

  3. Renate

    Wonderful work, as always, Taneya! Do tell – how’d you accomplish the overlapping pics of the segments?


  4. taneya (Post author)

    Renate – I’ll send you directions later today!

  5. Renate

    Thanks! You’re the “bestest”! 🙂


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