Won't the offspring of the survivors in Wayward Pines eventually become abbies too?

I don't know.

I don’t care.

My take was that it was an environmentally-driven change, like something had happened to Earth's general environment that was causing a genetic shift in response, like some kind of adaption.

I think the idea was that long enough had passed that the environment had recovered and that it was safe again for humans to become re-established.

I'm not sure it's the most sound genetic/environmental logic, but then again it's TV, not a post-doctoral seminar on human evolution.