Ancestry vs Ancestry test results different

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I’ve been working on my family tree using Ancestry for several years now and have made some discoveries through them. I recently took the Ancestry DNA test and the results came back very different than what I was expecting given what I know for a fact is true. My mother’s father was 100% British, born in England, as were all of his ancestors. Wouldn’t that alone make me approximately 25% Great Britain? In addition, I know on my father’s side that his father’s father’s mother’s family all came from Scotland. My Ancestry DNA test results were 66% Western European, 25% Irish, 6% Great Britain, 3% trace regions (Scandinavia, Finland). I had expected my percentage from Great Britain to be around 40%. Are these tests ever wrong? Should I take another type of test? Or should I have my mother, father and/or brother take an Autosomal test or another type of test? Thank you for any help you can give me!


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May 1, 2017 5:27 pm

You would probably get the best explanations for how this geographic ethnicity DNA works from the links on the Ancestry website. But in a nutshell: you get exactly one half of your dna from each of your parents, but you never know which half. For instance, if your mother was exactly 50% Great Britain and 50% Eastern European, you would get half of that. But that doesn’t mean 25% GB and 25% EE – think of it like a big pie that you cut in half – you get half of the pie, but it can be cut in half just about anywhere. So that 50% that you get from your Mom could be 50%GB, or 49% GB and 1%EE…get it? So siblings could potentially have VERY different dna ethnicities. And even if “all your ancestors came from Great Britain”…if you go back far enough, our ancestors all migrated from somewhere else. And so it gets a lot more complicated than just a nationality being handed down. (Now that of course is looking only at the autosomal dna). Hope this helps!

April 25, 2017 10:28 am

I am no expert, to be sure, but I did some digging and found this article very helpful:

It tells me that Ancestry does not perform Y chromosome tests, so all the results would exclude male specific DNA, right?

Also, the phrase you used “as were all of his ancestors” is a bit of a broad brush. Historically speaking, folks moved around a lot more before the invention of things like paper, much less of language. These wanderings all leave their mark, no matter how long ago. Surprises are inevitable, embrace them 🙂

Sally Jones
April 5, 2017 10:08 am

Hi Kelly,

Yours is an example of how fascinating each person’s DNA is. As you know, each person’s DNA is different and that includes the percentage of ethnicity they inherit from each parent, grandparent, etc. It would be interesting to see what your brother’s, mother’s and father’s results show. But it’s important to understand that today’s DNA Ancestry tests are still evolving and improving in terms of how they search for certain genetic markers and which ones they search for. I hope this helps!