One of the interesting things that people have discovered as a result of DNA testing is family secrets that would have otherwise been taken to someone’s grave are being brought to light. Some people have discovered that who they thought was their biological parent was not, others have discovered half-siblings they never knew about. Occasionally there are discoveries further up the line where grandparents or great-grandparents are not lining up with DNA as they should. In the genealogy world, we call these NPE. Although originally the acronym was for non-paternal event, sometimes people use the term a little more generally as Not Parent Expected. I don’t have any statistics to back me up, but I think the occurrence of these events is pretty rare. Naturally, though, these things have got people a little paranoid. I was very relieved to discover a maternal uncle and a paternal aunt as my top matches when I got my DNA results from Ancestry. Some people get DNA results and then they wonder, is this normal? Obviously no one wants to open up a big can of worms in their family where it isn’t warranted, so here I’d like to discuss what is normal and what is not normal. I still highly recommend taking your questions to a genetic genealogy group on Facebook before opening the can of worms, though. But at least you’ll save yourself the trip by ruling out these completely normal things.

When we talk about DNA results we are talking about two things: ethnicity estimates and DNA matches. I have a lot of disdain for ethnicity estimates so I’m going to tell you right off the bat that if your “is this normal” question pertains to your ethnicity estimate, my answer will be yes. Someone once said that these estimates are good dinner party talk but they’re really not good for much else, and I agree. The first thing to know about ethnicity estimates is that they are just estimates. If you look at the earth from space you are not going to see the artificial lines we have created to mark boundaries between countries. Further, people are always moving around. I am told my Scottish ancestors mingled with Vikings, so when I get “Scandinavia” as an estimate despite having no Scandinavian ancestry, I understand this to refer to that. Small percentages are especially suspect. The second thing to know is that each company will have different estimates because of the different reference populations they use when calculating said estimates. Finally, as each company refines their algorithms and adds more data to their calculations, these are likely to change. So if you’re wondering “why do I have Z ethnicity when my family tree doesn’t show any Z ethnicity?” It’s definitely not because you have an NPE in your tree or even because you had an ancestor with Z ethnicity that you haven’t discovered yet.

The second part of DNA results is your matches. If you have a known match, i.e., you know how you are related to this person, and are wondering if the amount of DNA you share with someone is too low or too high, the first thing to do is name your relationship. You can see my post What is a Cousin for more information or just use this handy cousin calculator. Once you know your relationship to someone, you need to use this DNApainter tool to see what the range is. Even between parent and child there is a small range of acceptable shared cMs. If the amount of DNA you share with this person falls within that range, then there’s no problem, everything is normal. Here’s an assignment: go see what the acceptable range for a third cousin (3C) is. Do you see that it is completely normal for third cousins NOT to share any DNA at all? In fact, you will see that once you get past second cousins (2C), it is possible to be related to someone and not share any DNA. No need to get into a tizzy because you don’t share DNA with a second cousin once removed (2C1R). It doesn’t mean your parents/grandparents/great-grandparents aren’t your parents/grandparents/great-grandparents. It just means you and this particular cousin didn’t inherit any of the same DNA that would tell the company that you are cousins.

If you have a match that you don’t know, and the amount of shared cMs is really high, you might also be concerned that there is something out of the ordinary. But keep in mind that just as it is possible to share no DNA with a second cousin once removed, it is possible to share up to 316cM. You may think, I know all my close cousins, is this cousin the result of a NPE of a relative of mine? You may know all your close cousins, but do you know all your second cousins and their descendants? Don’t assume NPE until you can verify that this person doesn’t fit into your family tree as they should. When you hear hooves, think horses not zebras.

What SHOULD you worry about? Not sharing any DNA with someone who is a second cousin or closer. Sharing less DNA than the range tells you you should share. Sharing more DNA than the range tells you you should share. Sharing over 500cMs with a complete stranger when you are certain of everyone in your tree up to the second cousin level. If you verified your relationship through the cousin calculator (and let me tell you, watching a group of people try to figure out how someone is related to someone else tells me most people don’t understand cousins) and then checked the DNApainter tool and something seems amiss, then by all means bring it to the attention of a group that deals with these kinds of things on Facebook. Otherwise you’re going to end up with this post in response to your query.