Interpreting MyHeritage DNA Match of 973cM?

Question

I just got a DNA match at MyHeritage with 973 cM, in common, which says first cousin. My mother had one brother, and it's from her side of the family. He had a son, who passed at a young age.

I am a novice, and some of the answers I have gotten are over my head. Being dyslexic has made it more difficult for me to understand. I have to read, reread and then reread again, to try to get the gist (which I am not getting).

I have common matches to her, from my Grandmas side (Biamtones) my Grandpa side (Deni) also, but there is no one in the family to ask. She was never told who her dad was, and her mother passed last year, as did my uncle. I am the oldest in the family, so no one to even hint at.

How can i figure this out?

I have asked her to send me her matches, to see how they match with me. Is there anything else I can do? I am not in the position to afford to pay a big fee.

She is my age, born in the city I was born in, and moved away at the age of 5. Her mother married and lived out of town. She is my top match. The next one we share is my Grandmas, brothers granddaughter LC who for some reason has 244 cM in common with Janice, while LC has 138 with me.

If it was our Great Grandfathers child, would it not have been a closer match then it shows to LC?

Plus she would not have my Grandpas family in her DNA matches?

Is that correct?

Answer 1

Just from the information you've provided, there seems to be a reasonable likelihood that your 1st cousin match may be your uncle's daughter (although, as @ColeValleyGirl points out, it might also be half-aunt/niece, somehow). However, the disparity in matches with LC is a bit puzzling.

It's difficult to draw conclusions from individual pair-wise matches. You apparently have other cousin matches from both of your grandparents' families. If you can get access to your mystery cousin's match data, I would suggest using the DNA Painter "What Are the Odds" (WATO) tool:

https://dnapainter.com/tools/probability

Go back a couple of generations and build a descendant tree for both of your grandparents' ancestral families, filling in all the known DNA samples and corresponding match levels with your cousin. Add a few hypothetical places she might fit in the tree, and let the tool calculate the statistical likelihood of each hypothesis.

For hypotheses, you can be as creative as you like - you could, for example, hypothesize that your mother and uncle had a previously-unknown sibling (or half-sibling, even though the numbers don't seem to support it).

Ideally, you should see one hypothesis that's at least 10X as likely as the next best. That may take quite a few samples to achieve.

Also, don't assume that matching DNA came only through your grandparents. If your ancestral families lived in the same town for some number of generations, it's entirely possible that there are other common ancestors further back contributing to some of the match, or other scenarios (e.g., double cousins, if one of your grandmother's siblings married one of your grandfather's siblings - it's not uncommon for sisters to marry brothers).