I never got, "the talk" and in consequence, when I hit puberty, it confused/scared me. I never asked why my body hurt incredibly, why I smelled now, why I was growing odd hairs, why I was getting boners. I didn't think to ask because it was my body and I treated it as a taboo topic. Then my dad died and finding this stuff out from mom/the internet doesn't quite cut it.
Tl;dr - There is no telling what might happen to the parents or child, so the, "talk" is important as a precaution.