As sad as the story is, I find it a bit of a stretch that a boy would "naturally" tear off a dress at age 2 either, since children of both sexes were dressed in such manners for many centuries. It seems much more likely that he'd picked up cues that he was supposed to be male and was rejecting things that his culture told him were female.
It's probably both cultural and biological in this case, I'd imagine. (it could be that he'd learned that dresses were associated with females through cultural conditioning, but he mentally knew on some level [maybe subconscious] that he was male, or something along those lines.)
