Fun with DNA matches

[SueMay]

So, I have a DNA match of 64 cM across 3 segments with a guy called David. This has been a challenge to work out but, with the help of the Masterclass, I have managed to work out other matches and felt fairly confident that I could do it again. Having studied both his tree and mine, I found we had ancestors with the same surname, both born in Ireland, living in Scotland and close in age. This being on his maternal grandfather’s branch and mine being on my maternal grandfather’s branch. I haven’t been able to confirm with documents but I feel sure that I this is our link which, if correct, makes us 4th cousins twice removed.

Interestingly, David’s maternal grandmother come from Lincolnshire which is also where I have ancestors on my father’s branch.

Other DNA matches which are also linked to David are his 1st cousin, Charlotte, with whom I have a match of 52 cM across 2 segments. And, his 1st cousin once removed, Christopher, but my DNA match with him is only 22 cM across 1 segment and we are 5th cousins once removed. I realise that DNA passed down can differ and differences should be expected, however, I wouldn’t have expected such a big difference.

Could it be that David and I also have a match on his maternal grandmother’s side? I have searched but not found anything as yet.

Am I perhaps not understanding it all or could I perhaps have the link incorrect?

I must admit that I am having fun with working out all my DNA matches and would be very interested to hear what others think.

Many thanks,
Sue

 

[Pauline]

If you look at the shared DNA chart in Peter's masterclass you'll see the the ranges for the amount of DNA you might share with a particular degree of cousin are pretty large. As an example, I have a documented 6th cousin 1 x removed with whom I share 40 cM across 5 segments, which is more than I share with two 3rd cousins in the same line.

The shared DNA chart shows the average expected for a 6C1R is 16 cM but the range is 0-72 cM, so 40 cM sits comfortably within that. Yet I do wonder if I might share a second link with this particular match but that is more to do with the matches we share, two of whom don't share our known link. In other words we need to look at more than just the amount of DNA we share with a particular person.

As for whether you and David might share a second link in Lincolnshire, you probably need to start by taking a closer look in the records. As another example, I have a documented 3rd cousin with whom I share ancestors in Kent, and we have lots of shared matches to back up that link. However, he and I also both have ancestors in a Gloucestershire town, and I recently discovered that we have shared relatives there. That is, I haven't found any evidence of any shared ancestry there, but a nephew of one of my ancestors married a niece of one of his, so their descendants are related to both of us.

It is perhaps worth reiterating that adding more people into Lost Cousins can help with untangling relationships with DNA matches. As well as the possibility of connecting with new cousins who may have some of the answers, the actual process of tracking down more descendants via the censuses leads to discovering new surnames to search for in our DNA matches.