Originally posted by Chap
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SNPs determine haplogroups (for example, J1 and J2) and subclades within haplogroups (for example, J1b and J1e), and these are different from DYS markers. IMO, it's not much good to compare haplotypes unless you know both your and the other person's haplogroup and subclade because people with similar sets of DYS markers can belong to different subclades and sometimes even to different haplogroups. (This is up to a certain point and depending on the haplogroup; the more markers there are to compare, and the more similarity between the haplotypes, the less likely they will belong to different haplogroups/subclades). If you check out the J1 results in the J Project, you'll see that a number of the haplotypes are very similar, but belong to different subclades. This means that although two haplotypes may be similar, if they belong to different subclades, they're not as closely related as persons with differing haplotypes who are within the same subclade. So SNPs take precedence over DYS values. That's why you need to be cautiously optimistic when you find a similar haplotype in databases such as ySearch, as your degree of relationship will be tenuous unless you both know your subclades. However, if you find a very close match, for example a 65/67 match, then you should be related within a genealogic time frame and you should be in the same haplogroup and subclade. For basic answers to a lot of questions, choose "FAQ" at the top of the FTDNA homepage.
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