I took the ancestry.com test as did my 1/2 uncle and 1/2 aunt on my mom's side. I am trying to locate their mother's parents, my grandmother's parents.

I was able to narrow the matches down to some 2nd and 3rd cousins for my Uncle and Aunt but I am having difficulty determining which cousins would be on the paternal and which would be the maternal.

My grandmother was a foster child and we know nothing about her past, no birth certificate, no birth location, nothing.

There is one second cousin who shares 508 cM with my Uncle and she is one generation above him so I was able to determine that she was likely a 1st cousin 1x removed which would mean that her parent is likely a sibling of my grandmother's parent. I was able to locate all of this person's siblings and I have even reached out to second and third cousins but no one has any information that would help me determine which side I am looking on.

How do I determine if I am seeing my grandmother's maternal or paternal side?

I also uploaded the raw dna to gedmatch but haven't been able to get any further.

2 Answers 2


How do I determine if I am seeing my grandmother's maternal or paternal side?

If I correctly understood the question, the answer will be:

Unfortunately, there are no way to determine it. You need your grandmother's cousins (or uncle/aunt, or their ancestors) from at least ONE side - paternal or maternal - to split the matches into categories. If you grandmother was a foster child, it is generally impossible.

Also the DNA heritage from particular person with every generation becomes lower and lower. So it is more and more difficult to state something precisely.

Please add more information into your question. I may guess that it is probable, but not common, if you really taken DNA test from your grandmother. Also what do you mean as 1/2 uncle and aunt? Maybe graphical representation will be more obvious.

  • What I mean by 1/2 uncle and aunt is that they and my mom share a mother, my grandmother but they have different fathers. So when I am on Ancestry and I filter by either my 1/2 uncle or aunt then see who we match I know for certain that the matches come from my mother's mother's side but that is where I get stuck. Am I looking at my mother's mother's mother's side or her father's side? There are two potential people that could be one of her parents but one is male and one is female. I am at a loss.
    – Vicky Hunt
    Nov 7, 2017 at 19:23

You can take a Mitochondrial DNA (mtDNA) test, to see if the older generation cousin is related through her mother's mother. Mitochondrial DNA only passes from mother to child, so if your mother's mother's mother and the cousin's mother were sisters, and these sisters had the same mother, you will all have the same mtDNA.

Your 1/2 uncle and aunt and you all relate through fully female lines, so only one of you needs to be tested. The three of you have the same mtDNA. You just need to have the cousin test, too.

Match = you descend from your cousin's mother's sister.

No Match = you descend from your cousin's mother's brother, or your cousin's father's sibling.

This only gives a 25% chance of success, but you may get more matches having your mtDNA in a database. You'd need to test more of your cousin's cousins to narrow it down further.

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