I just started looking into the longest segment a few days ago because on my mother's paternal side....her number one DNA match shows up as a possible 2nd cousin. But all of my mother's 1st and 2nd cousins on her maternal side have a much lower Longest Segment than this person on her paternal side. Is it because a half sibling or cousin is in the lineage > If you could read these results and let me know how my mother is related to this person (approx) that would be a huge help. Shared DNA: 205 cM across 6 segments Unweighted shared DNA: 205 cM Longest segment: 114 cM
Hi R.W., It's normal for paternal matches to have longer segments. This article about segment pattern analysis may be helpful to you: familylocket.com/new-tool-for-dna-segment-pattern-analysis/ . This is the section that answers your question, in part: Why do I share longer segments with my paternal grandparents? Men and women have different recombination rates. The ISOGG wiki states, “Males average about 27 crossovers per child and females average about 41 crossovers per child.” It makes sense that if there are more crossovers when females have children, their grandchildren will share more segments and those segments will be a little smaller. Your match sharing 205 cM is slightly more likely to be a 2nd cousin than a half 2nd cousin or 2C1R, but the probabilities are very similar. There are several other possible relationships as well (like 1C2R, Half 1C2R, 1C3R, 3C, 2C2R, etc. I determined this using the Shared cM Project tool at DNA painter: dnapainter.com/tools/sharedcmv4. Hope that helps! -Nicole
