I am not very good at talking about segments etc., but I want to see if I understand this. My second cousin on my maternal side tested. I have noticed that we have some matches in common. When I look more closely though, she doesn't match the other person on the same chromosome as I do. For example: one of the matches is a person with a grandfather who was said to be the son of someone I share a surname with. We communicated and her people and mine were from the same basic location. Even possibly the same neighborhood - so it corroborated what she had heard about her real ancestry. Not the exact father but the same surname. Then my 2nd cousin tested. I guess I expected a match would confirm the surname on in the same place on the chromosome. However, her match is greater on a different chromosome. Would that suggest we are matching different parts of the same tree. One of us the male line and one picking up the female line? Does that make sense? The images from Chromosome Browser: https://www.dropbox.com/sh/wnklaa0b6w7emtf/4-zQBbD4Qr I want to see if I am correctly interpreting the differences in matches. Chris

Chris Treat each shared segment (with any Match) as coming from a Common Ancestor. With multiple shared segments, the Common Ancestors can be the same or different. With a 2nd cousin you may get several shared segments. The odds are high that they are all, or at least mostly, from your shared great grandparents. The closer the Common Ancestor the more likely it is that the CA provided the segments you share. The same CA provided many segments (actually a full set of Chr) to your grandparent, who in turn passed half of that to your parent. Now that same great grandparent CA passed a full set of Chr to the child who is the grandparent of your 2nd cousin. But only 50% of that atDNA would be the same as that passed to your grandparent. Etc. So these segments that the great grandfather CA passed down came from his/her parents - and different segments could/would have come from different ancestors of the great grandparent CA. And there is always the chance, particularly in endogamous populations, that there was another CA for you and your 2nd cousin, not from your well known great grandparent. Jim - Sent from my iPhone - FaceTime! On Oct 20, 2013, at 11:21 AM, Christina Hunt <chrisnina@gmail.com> wrote: > I am not very good at talking about segments etc., but I want to see if I > understand this. My second cousin on my maternal side tested. I have noticed > that we have some matches in common. When I look more closely though, she > doesn't match the other person on the same chromosome as I do. > > For example: one of the matches is a person with a grandfather who was said to > be the son of someone I share a surname with. We communicated and her people > and mine were from the same basic location. Even possibly the same neighborhood > - so it corroborated what she had heard about her real ancestry. Not the exact > father but the same surname. Then my 2nd cousin tested. I guess I expected a > match would confirm the surname on in the same place on the chromosome. > However, her match is greater on a different chromosome. Would that suggest we > are matching different parts of the same tree. One of us the male line and one > picking up the female line? > Does that make sense? > The images from Chromosome Browser: > https://www.dropbox.com/sh/wnklaa0b6w7emtf/4-zQBbD4Qr > > I want to see if I am correctly interpreting the differences in matches. > Chris