I've been using GEDmatch for a few months now and recently discovered Genome Mate. I love both of them and how they work in tandem. I thought I understood how matches work but now I'm having doubts. I am working on doing a copy/paste of one-to-one results for the top matches in a one-to-many search on GEDmatch over to Genome Mate. It's going pretty fast and I love that I can actually see which of my matches are likely related to me through certain common ancestors since we all match on a certain segment of a particular chromosome. However, I'm confused about one segment that shows a triangulation match on Genome Mate with me, my second cousin once removed (who I actually know), and a third person. Our match is from position 61,566 through 7,546,875 on chromosome 4, representing 17 cMs. Genome Mate shows a match for all of us on this segment, and when I do a one-to-one compare on GEDmatch between my second cousin once removed and me, then another compare between the third person and me, it shows I match both of them on this segment. What is confusing me is when I do a one-to-one compare between my second cousin once removed and the third person, there is no match on chromosome 4 at all! How can that be?