I am a novice at this DNA business so this might sound stupid but I have to ask. Two men test identical at 67 markers and have a paper trail to their common ancestor. Along comes a third man who also matches the first two exactly but his paper trail leads to a cousin of the common ancestor of the first two men. So all three men are exact matches but their common ancestor is now two generations farther back. Can anyone explain how that works? It seems to me that someone's paper trail is in error and the DNA is saying exactly that.