I am a project administrator of two atDNA projects. When dealing with a spread sheet of several ICW cousin matches downloaded from the GAP, should I discard all segments less than 10 cMs or should that number be closer to 7 cMs when the paperwork trail supports relationships? I initially went through the list and deleted everything below 10 but was concerned about discarding some of the 7, 8, and 9 matches as some had the same start or end points with others. Also, how should I handle matches on the same chromosome with breaks in the segments? Thanks. Connie Bradshaw John Carson of WNC Bradshaw & Harris

Dear Connie, There is no easy answer to this question. The question should be answered based on how much time you have to investigate HIRs less than 10 cMs and the total quantity of HIRs you have less than 10 cMs. I personally attempt to get pedigree charts for all my Family Finder matches (threshold 7.7 cMs) and 23andMe matches (threshold 7 cMs). I retain all HIRs over 3.5 cMs from my Family Finder matches in my personal comprehensive match lists. You could consider increasing this threshold to 5 cMs, but you will be deleting a fair number of IBD HIRs if you set the threshold much higher than 5 cMs. Keep in mind that the point at which there is a 50/50 split between IBD HIRs and IBS HIRs is around 7 cMs. If there is a strong paper trail supporting a shared ancestor for HIRs as short as 2-3 cMs you should retain that information. In terms of HIRs on the same chromosome that are in close proximity to each other, I suggest caution. Many of these are secondary to crossovers that occurred at that location, particularly if the breaks are of any significant length (over 5 cMs or so). Some of the breaks are artificial and are secondary to genotyping errors. In such cases it is hard to be certain if there is a genotyping error, particularly if you don't have the raw data for your match. In any case, if there is a relatively short break in what would otherwise be a long HIR consider the possibility of a genotyping error as the cause for the break. Sincerely, Tim Janzen -----Original Message----- From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Rvsailor@aol.com Sent: Thursday, November 21, 2013 5:56 AM To: autosomal-dna@rootsweb.com Subject: [AUTOSOMAL-DNA] Length of Segments of Shared cMs I am a project administrator of two atDNA projects. When dealing with a spread sheet of several ICW cousin matches downloaded from the GAP, should I discard all segments less than 10 cMs or should that number be closer to 7 cMs when the paperwork trail supports relationships? I initially went through the list and deleted everything below 10 but was concerned about discarding some of the 7, 8, and 9 matches as some had the same start or end points with others. Also, how should I handle matches on the same chromosome with breaks in the segments? Thanks. Connie Bradshaw