Help with DNA puzzle please (it's driving me nuts!)

[Mpb56]

I have three DNA matches (GP, AP AND JA) and I am struggling to find the MRCA. I have used DNA Painter (please see attached photo) and all three match on my 2nd maternal chromosome. I have created a family tree for GP and AP and I believe that AP is a grand nephew of GP.

I have managed to add JA to my family tree and from this have found our MRCA which makes JA my 3rd cousin.

What I am struggling to do is to link them all up and add GP and AP to my family tree. My limited understanding of DNA suggests that because all three have overlapping matching DNA they should have a the same MRCA - what am I missing? Any thoughts on the way forward would be gratefully received!

[CorleyMiller]

Are these matches all on the same DNA testing site, if so do you get an indication of triangulation between the shared segments?

Have you taken the tree of GP back to the level indicated by the DNA Painter Shared cM tool when inputting their total cM match size?

[Mpb56]

Hi Corley

Thank you for your reply!

GP and JA are from My Heritage and triangulation is indicated for me and them. AP is from 23 and me so the triangulation comes from DNA painter.

I have taken the tree of GP back to her great great grandparents (about 1783) but am struggling to get further back

[CorleyMiller]

If you've gone sideways and down from the great great grandparents to include all their siblings and still no link then I'm afraid it is either further back or there's possibly a NPE involved.

From my experience the size of the segments do seem too big for it to really really far back.

What are the total size of these matches (i.e. all chromosomes)?

Any clues from shared matches? Have you tried MH's cluster tool which groups matches likely to be descended from a common ancestor?

[AngelaR]

I'm sorry to ask a stupid question. I understood the whole of the posts above (unfortnately with no new suggestions to add) except for the term MRCA. I assume CA is common ancestor but I haven't guessed the other bit...

[CorleyMiller]

Most recent

[Mpb56]

Thank you Corley.

I did wonder about a NPE.

JA total 73.6 cM across 2 segments, GP total 67.7 cM across 1 segment and AP 65 cm across 2 segments.

Shared matches don't seem to bring anything to the party as most don't have trees and are not talking to me (I don't take it personally!). Although they do confirm this group is on my maternal side.

I've tried the MH cluster tool but JA and GP are not clustered.

[AngelaR]

Most recent

Thank you Corley! All new information is good

[rsel]

GP and JA are from My Heritage and triangulation is indicated for me and them. AP is from 23 and me so the triangulation comes from DNA painter.

Hi, probably a silly question but you haven't said, are you sure they all on your maternal side ?  If you have just used DNA painter all its telling you is that they are overlapping on the same segment, but it could be one match is maternal and the other is paternal, so there is no actual match ?

Richard