Grandfather

Donna47460

My maternal grandfather is questionable. If I have no DNA matches with his family tree, can I assume he is not my grandfather?

Adrian Bruce1

@Donna47460 - do you know if any of his close relatives have tested with the same people that you tested with? For instance, I don't know which of my relatives have tested, if I don't get a match, because that information is correctly judged to be confidential.

So unless you know that a number of his close relatives have tested with "your" provider, then no, you can't assume that he isn't your grandfather.

PiioN

You would need to test your maternal cousin, if you share one grandparent in common, you are half cousins, if 2 then full. Dna is about relationships, and when family is involved then relative relationships reveal the actual biological relationships. And social relationships are no less important, if there was a abandoned girlfriend or some radical changes going on in life at the time.

Gordon Collett

As stated in the previous two comments, DNA matching is tricky. It is important understand at least a bit about them starting with the fact that matches are not Yes and No, but rather, More Likely and Less Likely. This is because they are based on shared DNA as measured in Centimorgans.

Here is a chart that describes the expected range of shared centimorgans for various relationships: https://dnapainter.com/tools/sharedcmv4

The best way to see if you have a DNA connection to your maternal grandfather is for both you and him to be tested. As the chart shows, you and he on average will share 887 Cm of DNA but the current statistical range suggesting a likely relationship is from 485 to 1486 Cm. If you and he share far less than 485, then it is highly unlikely you are connected through DNA. A number far larger than 1486 would be biologically impossible unless you are his clone.

However, if only you and a second cousin twice removed have tested, the two of you could share 0 to 244 Cm. In other words, you and that cousin may share no DNA whatsoever and still both be descended from that maternal grandfather of yours.

This is why there is generally a recommendation that if one is really trying to figure out DNA relationships, you should test as many people as possible with various relationships for you. I'm not really sure about this, but I would think that the best strategy would be to try to get descendants of that maternal grandfather's siblings to test. If they all match nicely in a way that is consistent with their common ancestor being the parents of your grandfather and you do not match with any of them, then that would cast doubt on your DNA relationship with your grandfather.

Donna47460

Thanks for all your comments. My grandfather died in 1924 at the age of 25. Unfortunately he had no (other) children. This may be a tough one to solve.

Gordon Collett

Did he have any siblings?