- The 1/billion chance is a red herring. The probability of any unique 19 nt sequence occurring is (¼)19. You could pull out nearly any 19nt sequence in and species at almost any loci and make the same claim.
No, you've misunderstood.
They are not drawing a Kind of Hearts from a deck of cards and claiming that the probability was 1/52. That's what you're saying they're doing, and that would indeed be stupid.
They are comparing two shuffled decks of cards, and finding a subsequence that exists in both decks, and then claiming that the probability of this happening is low. Even this isn't perfectly valid (and we can go into why), but it's slightly more valid than what you're giving them credit for, and I would like to see it properly addressed.