I am a DNA learner and often refine my understanding from the discussions on this board but have hit an issue that seems counter-intuitive. I’d like some guidance and references so I can improve my methodology.
A family (father and two sons) recently posted their results on MH and show a match with my family member, whose results were uploaded to MH from Anc. There’s a cluster of matches on ANC and MH connected to a family who emigrated from Hull to Australia. Both families have well-researched trees. Genealogy suggests they’re likely to be our 4th cousins (at one or two removes) on the maternal line (and ANC picks this up) although there is possibly a further link to the paternal line six or seven generations back.
Using the chromosome browser on MH, my family member (J) and the father (D) show a 67.8cM match, with 3 shared segments on Chr. 5 and 13. Conveniently, the match with son P shows on Chr 13 (39.5cM over 2 segs) and with son M on Chr. 5 (26.2cM).
Then things get challenging for me:
Total number of matches with J (excluding family members) on MH:
D (father): 37(triangulated matches: 9 on Chr 5, 2 on Chr 13)
P (son): 37(5 triangulated matches over 2 segs on Chr 13)
M (son): 87(41 triangulated matches over 1 seg on Chr 5)
Shared matches:
Between all 4 of the group (J+D+P+M): 2
Between J, D and P: 7
Between J, D and M: 13
Between J, P and M (the two sons): 8
I just can’t get my head around how, compared to his father D, son M can have more than twice the number of matches with J.
I understand some of M’s exclusive matches may include related members, which his father’s may not, but can’t spot a large cluster which would bump M’s numbers up so much. I have looked at the sons’ mother’s line and her family seems to have emigrated to Australia from a completely different part of England. It seems unlikely there would be any interference - and if there was, there would be differences between the triangulated father/son segments on Chr 5 and Chr 13, wouldn’t there?
This is my first try at explaining a DNA puzzle so apologies for not being more concise. I don’t expect a solution but would like to know where to look for some related reading to help me interpret what is going on here.
