DNA Q&A: The Case of Mom’s Missing Surname

By Diahan Southard Premium

Q: I am really puzzled. My father submitted his DNA to Ancestry and I did too. I have many shared matches with him. But, my mother is deceased so there is no DNA from her. I have many DNA matches from her maternal side, but I am not finding one person with her father’s surname of Forbish. Does this mean he was not her biological father? Thank you for any light you can shed on this predicament.

A: Many genealogists are taking ahold of the idea that testing more known family members gives you test results that are better able to help in solving family history questions. And while this is entirely true, it can sometimes just produce more data that we have to try to search through.

You are correct in that as soon as you have one known family member tested you have a clue that can help you identify at least which branch of your tree some of your unknown branches might belong to. We do this primarily by using the Shared Matches tool. Let’s say your known first cousin, Ralph, has DNA tested. You and Ralph share paternal grandparents Marcus and Hilda. That means that anyone else who is sharing DNA with you and Ralph should also be related to Marcus and Hilda in some way. So you can go through your DNA match list and mark those particular matches as paternal side, even if you don’t quite know how they connect. It sounds like this is exactly what you have done with both your paternal and maternal side cousins who have tested.

Focusing on cousin matches may help with missing surname information on DNA test results.

Counting on Cousins

My first follow up question for a missing surname would be “Do you have any first cousins on your mom’s side tested?” If you do, then we can look at the total amount of shared DNA with that first cousin to make sure you are full first cousins, as opposed to half first cousins (which would indicate that your mom was just a half-sibling to your aunt or uncle). Without a direct test of your relationship like that, we can only be left with speculation.

However, we might be able to turn speculation into something more if you have a close match that you know is not related on your dad’s side (not sharing any DNA with your paternal cousins) and doesn’t seem to be related on your mom’s side (not sharing DNA with your known maternal cousins). If you have someone like that in your match list, it is time to investigate.

A close match, meaning a second cousin or closer, who doesn’t seem to match anyone else, could represent a great grandparent couple that was previously unknown to you.

If you do not have a match like this, but you still don’t see the missing surname in your match list, it could just be that no one from that branch of your tree has tested yet. This is often the case if your line has recently immigrated into the United States. Your best course of action moving forward is to directly test someone you know is related to this Forbish line, and then analyze the results.

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