Larry Your explanation is excellent, and the light bulb came on - thanks for your brevity and clarity. Now - that explains one location. How many ACTGs are there in 7.7cM? I thought the point was that with a long segment we could rely on the fact that it was an exact match. I guess the point is, in a way, it is an exact match. So what's the probability of another segment of exactly the same long length being an exact match, just with a scrambled up/different arrangement of ACTGs? If in fact groups of 3, 4 or 5 matches turn out to not be related, then the odds must be high. Although I understand how the matching is done, and how it can create many different combinations from the same segment, it still seems ... unusual? ... that these will match several others from the relatively small community of folks who have taken this test. Jim - Sent from my iPhone - FaceTime! On Jan 6, 2012, at 5:14 PM, Larry Vick <[email protected]> wrote: > Jim, > > If you have AG at a location and you have two matches one of whom has AA and the other has GG, you will match both, but they will not match each other. FF has no way to know which of your parents you inherited the A from and which you inherited the G from. > > Regards, > > Larry