DNA: Test All Your Siblings

I’m on a hunt for the parents of the first of our Morrisseys in the U.S. James (see his profile pages) was born in Abbeyleix, County Laois, Ireland in 1832. The only indication of his parents are on the back of his marriage record: Michael Morrissey and Catherine King. I’ve yet to uncover any siblings, or other blood relations in my extensive research on James, including online Irish records like Griffith’s or Catholic Parish Records.

James being my great grandfather, you’d think it would be a piece of cake. Nope. Nopedy, nope, nope. I think that part of the issue is age. My dad was 48 when I was born (I’m the youngest of 6 kids.) My dad was 3rd out of 6 kids.  My paternal grandfather (Ambrose) was 49 when my dad was born. James was 43 when Ambrose was born and Ambrose was 10th out of 11 kids. Each is old enough to be a grandparent when their kids were born. What’s 4 generations on paper, could be 7 generations for another family or in another’s DNA. Those 7 generations outside of the range of accuracy for an autosomal test.

Y-DNA testing (of my brother) has yet to offer any helpful insight.

Back to the title of my post: Test all of your siblings.

I’ve tested 2 of my 4 living siblings. So, 3 kids in the same family. My mom is still with us, so I’ve tested her. One of my resolutions for 2018 is to work all of those paternal matches. So, if someone doesn’t match mom, their labelled paternal. I add them to an excel spreadsheet an farm all the data I can. I’ve gotten through all of my 4th cousin matches on Ancestry for me, my brother and my sister.

Here are a few things I’ve noticed in crunching the data.

  1. Test taker “B.” My brother matches “B” at 106 cMs. My sister matches at only at 33 cMs. I don’t match this person at all! We have a confirmed paternal 1st cousin who matches “B.”
  2. Test Taker “J.” My brother matches at 92 cMs. My paternal 1st cousin matches “J.” Neither my sister, nor I match “J.”
  3. Our relationship with “P” was identified based on an online tree. We’re 3rd cousins, once removed. “P” matches me, my brother, my sister and my paternal 1st cousin. But at small amounts. 13 cMs, 24 cMs and 14 cMs respectively. While, these numbers fit into the 3C1R range in the Shared cM Project, they aren’t what I expected.

In each case, the lack of sibling tests would have left me without DNA confirmation of several lines on my tree. I wouldn’t have matches “B” or “J,” and “P” would have been such a small match that I probably would have overlooked it.

So, test everyone you can. And get those spreadsheets warmed up!

You may also like