Originally posted by Ericjle
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The total number of SNP differences between a match can only be 30.
So if a person tests and comes back with 29 Novel SNPs, in order to match, the other person would only be allowed 1 additional solitary differing SNP value. Although they should share the 6 SNPs that define the clade, so the real total variation "allowed" for them in such a case would be 7 novel SNPs, compared to 23 for your kit. Not likely in either case unless your respective branches are extreme outliers in SNP mutation rates, just in differing directions(highly stable vs highly unstable).
As it is, with my results back, the discussion here is largely moot for me, I have 44 people who match closely enough for me to see them through BigY, and they're all within two steps of my currently assigned terminal SNP so my tree can branch up to 3 more time before I lose any of them.
I just have the current mystery of how the 2 kits on my terminal SNP aren't STR matches(although with 19 and 20 differing SNPs respectively 8&9 of which are named SNPs, I could guess as to how; interestingly, I also share a unique SNP with each match that isn't shared with the other but Biology is often messy), while most of the other 42 BigY Matches are. Although the closest of those 42 matches as per TiP don't cross the 50% point(@111 markers) until 18 to 20 generations back, so still not likely to be close enough to prove "Genealogically useful" particularly given none of the surnames match and 5 generations takes me back to 1800 on that line.
Edit: And I just checked to be sure, my most distant matches have 30 non-matching SNPs(with me, not my Terminal), so that does seem to be the cutoff.
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