As I mentioned in this post, I have a funny problem on Chromosome 10. I have been working on this particular segment on this chromosome for a long time now. Here you can see the green of my great-aunt, and the other colours interrupting it. I’m guessing a piece of my grandma’s DNA inserted itself in a segment of my grandad’s DNA. Oddly, one of those matches is a distant cousin who shares other segments with my great-aunt.

I’ve been hearing the term “pile up” a lot and I’ve been reading and re-reading to try to understand what that means. Visually, I think it looks like this:

All those people in that big ball share a similar segment on chromosome 10 with me. All of them. It’s more than a little suspicious. Perhaps some of them aren’t true matches? Someone said that maybe I’m just lucky, and they all do go back to a common ancestor, which is what I originally thought. With such a large group, there’s got to be more than a few who have family trees that go back far enough so that we can find a common ancestor. And there is, for some of them. A few of them share a common ancestor in Rhode Island in the 1600s. This particular ancestor has popped up again recently in another match (on Ancestry, so I can’t even check if it’s on the same chromosome). The rest? Don’t fit in with that group. They all seem to have Scottish ancestry. So am I descended from that family in Rhode Island or not?

I found this blog post by Roberta Estes while researching pile-ups and I liked the section titled “identical by population” because it gave me hope that this segment is matching two different populations, a Scottish one and the one that is this family in Rhode Island: “Think about this, if every European has between 1 and 4% Neanderthal DNA from just a few Neanderthal individuals that lived more than 20,000 years ago in Europe – why wouldn’t we occasionally trip over some common DNA from long ago that found its way into two different family lines.”

I think it’s also kind of neat because every time I ask about pile ups or read about them, I am reminded that we are in very new territory and there’s a lot we just don’t know. It hasn’t even been 100 years since we knew that DNA was a thing, and the very first home DNA tests came out less than 20 years ago. It is only now that DNA testing has become more mainstream that people are even able to see these pile ups. Eventually maybe we’ll have a better idea how to work with these segments. As Roberta writes: “Just because I don’t quite know how to interpret it today doesn’t mean it isn’t valid.  In time, maybe its full story will be revealed.”