This may have been pointed out before, but not where Google and I could find it.

Harry, speculating in Chapter 25:

Some intelligent engineer, then, had created the Source of Magic, and told it to pay attention to a particular DNA marker.

The obvious next thought was that this had something to do with "Atlantis".

Harry had asked Hermione about that earlier - on the train to Hogwarts, after hearing Draco say it - and so far as she knew, nothing more was known than the word itself.

It might have been pure legend. But it was also plausible enough that a civilization of magic-users, especially one from before the Interdict of Merlin, would have managed to blow itself up.

The line of reasoning continued: Atlantis had been an isolated civilization that had somehow brought into being the Source of Magic, and told it to serve only people with the Atlantean genetic marker, the blood of Atlantis.

Chapter 61:

"Worse than any peril I know," said Albus. "But probably not worse than whatever erased Atlantis from Time."

The Friendly AI Critical Failure Table:

34: The programmers and anyone else capable of explaining subsequent events are sent into temporal stasis, or a vantage point from which they can observe but not intervene. The rest of the world remains as before, except that psychic powers, ritual magic, alchemy, et cetera, begin to operate. All role-playing gamers gain special abilities corresponding to those of their favorite character.