Bob Two key things to remember: 1. You have two Chr 3s, one from Mom, one from Dad - you need to consider that the first two examples you gave may be on one Chr, or different (like night and day) Chrs. 2. As I understand it, FTDNA compares blocks of atDNA. So the very precise locations you've noted may just reflect they precise locations they've chosen for a comparison block. As such, we should not put too much stock into exact locations like this. Repeating, in other words: the start and end locations of shared segments should be taken as fuzzy (and not exact). In furtherance of this concept, every few months it seems like FTDNA modifies these positions slightly... Also refer to your own GEDmatch locations (from exactly the same data set). 23andMe would give you a third version, which also would be pretty close, but not usually exact. I use rounded numbers which are easier on my eyes - your example segment would be 150.8-161.2 If I ever get *done* mapping, I'll go back and try to refine the locations with the then current Build. It's not critical for assigning ancestors, it might be if you eventually want to determine where a particular SNP or gene came from - but I'm a long way from that analysis. Jim - Sent from my iPhone - FaceTime! On Dec 18, 2013, at 12:16 PM, "R&J Dickinson" <rgjad2@gmail.com> wrote: > FTDNA shows that I match person A on Chromosome 3 as follows: > > Chromosome Start Location End Location centiMorgans (cM) # of Matching > SNPs > > 3 150753777 161181771 8.77 > 2188 > > > > FTDNA shows person B, my cousin known from a paper trail, matches person C > as follows: > > Chromosome Start Location End Location centiMorgans (cM) > # of Matching SNPs > > 3 150753777 161181771 8.77 > 2188 > > > > However, FTDNA does not report that I match either person B, my cousin, or > person C and does not report that person B matches person A. If all four of > us match at the exact same place on Chromosome 3, is there a valid reason > that FTDNA does not show all of us as matches? > > > > Is it reasonable to conclude that the four of us are likely to have a common > ancestor? > > > > Incidentally Gedmach shows that I match person A as follows: > > Chromosome Start Location End Location centiMorgans (cM) > # of Matching SNPs > > 3 150617062 161081884 8.5 > 2109 > > > > Any comments or suggestions will be appreciated. > > > > Bob Dickinson > > > > ______________________________ > For answers to Frequently Asked Questions about mailing lists, please see: > http://dgmweb.net/MailingListFAQs.html > > > ------------------------------- > To unsubscribe from the list, please send an email to AUTOSOMAL-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message