dko_scOH - 11/4/2016 07:30

Single nucleotide polymorphism. Fancy way of saying one base pair switched from, say, a T to a G. The common DNA tests (including those run in crime labs) look instead at STRs, or short tandem repeats. These are useful to begin the sorting and will give you a broad predicted haplogroup. Haplogroup is confirmed and narrowed using SNPs. For example, I was assigned the predicted haplogroup R-M198 after STR testing. This is a clade that evolved over 10,000 years ago. SNP testing refined this to YP609, which is only a couple thousand years old. Below that I share SNPs with other testers as recently as the 1600s, possibly when my ancestors moved to Ulster while theirs stayed in Scotland. And below that, I have three "private" SNPs not seen in any other tester. If I can get third-, fourth-, fifth-cousins, etc., to start testing, we can find which individual had the first mutation.

This is how you build a genetic tree. A couple of generations from now, all you will have to do is send off some DNA and tap into this enormous forest of family trees, complete with all known names, dates, and relationships.