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-   -   Suprising Large DNA match (http://genealogistsforum.co.uk/forum/showthread.php?t=29861)

Bhx7 07-07-21 19:32

Suprising Large DNA match
 
Hi

I have had my DNA done through Ancestry for sometime and have had some quite good results which has helped me prove my previous research and extended it considerably further in places.

However, earlier this year I had a large DNA match of 520cM with someone out of the blue. From the story he was told he had always known his mother was not his grandfathers daughter, but her father was in fact a member of my family who owned a shop. It was close, the location of the shop was actually next to the Public House my Gt Grandparents had. So close enough.
His matching links to other members on Ancestry and also other forums, also prove beyond a shadow of a doubt that he definitely links to my paternal family. But how???

As his mother and grandmother are no longer around, there is no one to ask regarding who in my family line it was who is his biological grandfather. There are however, 4 possible candidates. My Gt Gt Grandfather, Gt Grandfather or 2 of my Gt Grandfathers brothers

With the link being so close I had assumed he would be my Gt Grandfathers grandson. However, my Gt Grandfather would have only been 15 and his grandmother would have benn 24! Not unheard of I know but a little concerning.

I have tried DNA Painter and no matter which way I try, I can't seem to come to a satisfactory conclusion.

However, there now seem to be a complete lack of my Gt Gt Grandmothers family DNA within his matches, which if he had been my Gt grandfathers or the other two brothers, surely he should have had?

So my Gt Gt Grandfather seems the most likely, but the DNA match is just too high, isn't it?

I hope all that makes sense.
Any insights would be gratefully recieved.

Thank you all in advance
Brian

kiterunner 07-07-21 21:44

DNA Painter lists the following possibilities for 520 cM:

Great-Great-Aunt / Uncle
Half-Great-Aunt / Uncle
Half First Cousin
First Cousin once removed
Half-Great-Niece / Nephew
Great-Great-Niece / Nephew
Great-Grandparent
Great-Aunt / Uncle
Half-Aunt / Uncle
First Cousin
Half-Niece / Nephew
Great-Niece / Nephew
Great-grandchild
Half-Great-Great-Niece / Nephew (very unlikely)
Half-Great-Great-Aunt / Uncle (very unlikely)
First Cousin twice removed (very unlikely)
Half First Cousin once removed (very unlikely)
Second Cousin (very unlikely)

kiterunner 07-07-21 21:51

If your 2xg-grandfather is the grandfather of your match, he would be your half first cousin twice removed.
If your great-grandfather is the grandfather of your match, he would be your half first cousin once removed.
If your great-grandfather's brother is the grandfather of your match, he would be your second cousin once removed.

The only one of these which comes up in the DNA Painter list is the second of those three, but it says "this relationship has a positive probability for 520cM in thednageek's table of probabilities, but falls outside the bounds of the recorded cM range (99th percentile)".

kiterunner 07-07-21 22:11

So, yes, I agree with you. Could he be related to you in two different ways?

Bhx7 08-07-21 00:43

Hi Kiterunner

I have looked into the possibility that there is a dual match but I cannot find any other connection as yet. I class myself as a fairly good researcher but this one has me stumped.

Also as stated he has no DNA link to my Gt Gt Grandmother on the paternal line, so although the DNA wouldn't suggest it, I am definitely looking at the conclusion that it can only be my Gt Gt Grandfather who can be his grandfather. Nothing else can make any sense. It just always comes back to the amount of DNA connection...

I have tried to get other family members to do a DNA test, so far without success.

It's intriguing and exciting to find another family member who is so closely related, but also frustrating that we can't 100% pin down our exact relationship.

I am determined to crack this mystery. The gentleman concerned is 80. Although we have managed to prove his lineage, it would be nice to finally be able to say definitively who his grandfather was.

Thanks Brian

kiterunner 08-07-21 08:54

He could download his raw DNA data from Ancestry and upload to GEDMatch where there is a tool "Are your parents related?"


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