(from The Legal Genealogist 6-8-2015)
It’s an acronym, short for Single Nucleotide Polymorphism.
Which, all in all, is such a mouthful that it’s no wonder it got shortened to SNP.
By definition, it’s “a DNA sequence variation occurring when a single nucleotide adenine (A), thymine (T), cytosine (C), or guanine (G]) in the genome (or other shared sequence) differs between members of a species or paired chromosomes in an individual.”1
That helps a lot, doesn’t it? (She says, with tongue in cheek and a huge dose of sarcasm.)
Think of it this way: a SNP is “a change in your DNA code at a specific point.”2 And we look at those changes to “confirm haplogroup assignments, to learn more about … deep ancestry and to rule out false positive matches” with possible cousins.3
So SNPs help us figure out exactly where we belong — on what branch of the human family tree — and who else ought to be hanging out on that branch with us.
Something to get snippy about, for sure.