Boring, Moronic Explanation
Anybody else notice this trend with newer horror movies to try to explain things in "scientific" (read: pseudo-scientific BS) terms. An unexplained, magical, mythical, Lovecraftian creature? Amazing concept. But a nonsensical, pseudo-scientific, ancient evolutionary mishap? Boring and intellectually insulting. If you want to concoct an intelligent, plausible sci-fi story with a realistic monster, go ahead--those stories can be brilliant--but don't create a fantasy monster and then try to explain it with gibberish exposition that includes the words "evolution" and "stem cells".
I honestly thought this was one of the best horror movies I had ever seen until the girl revealed her secret. It's truly a shame how these unimaginative imbecile writers manage to ruin potentially great films. They did the same thing with Digging Up The Marrow. "Hmm...an entire hidden world of underground monsters. Oh, I know, let's think of the dullest explanation possible. That'll be exciting!"