Avoiding a DNA Conclusion Jump

I’m always tentatively excited when I get a new match that appears to fit into my family of my great-great-grandparents, Samuel and Annie (Murphy) Neill. The key word is “tentative.” I’m always hoping it will help to to connect back to earlier generations of my Irish heritage.

This match, “S,” was noticed because it was a new match to one of my known DNA matches who is a Neill-Murphy descendant–LS in the image. When I looked at the shared matches I had with S, I noticed something: we didn’t share many of the known descendants of the Neill-Murphy relationship who I have already identified. We didn’t even share other unidentified matches that match several known Neill-Murphy descendants. It could just be the way the DNA passed down.

It could be something else.

I noticed that three Neill-Murphy descendants this new match shared with me were not spread through the entire family. The shared matches I had with the new match were all known descendants of one first cousin once removed of my grandfather Cecil Neill (a grandson of the Neill-Murphy relationship). We’ll call that woman “K.”

That could be because whatever bit of Neill-Murphy DNA S and I share was also the same bit that was passed down through K’s family and it was just the luck of the DNA inheritance. It could also be that that S is not a Neill-Murphy descendant at all. S and I could connect on some other family and S and the descendants of K share some non-Neill-Murphy connection. This is something to consider.

That’s one reason why in my notes, I don’t like to just put down the common ancestor but also the line of descent. It’s difficult to notice things of this type if you don’t.


If you’re looking to buy tests, AncestryDNA is offering some sales until this coming Father’s Day. Just remind the testee that there may be some unexpected discoveries. Some people welcome those. Others do not.

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