A stereotypical man is aggressive and competing. A stereotypical woman isn't aggressive and tends to cooperate rather than compete.
A stereotypical boy have toys like cars and plastic soldiers. A stereotypical girl have toys like barbie dolls.
So far I believed this is merely the result of the social conditioning, where boys taught to behave like a men, and girls are taught to behave like a women.
But it seems I need to think it again. I recently read this article about the girls in Salinas. They have a weird genetic disorder that makes boys born like a girl and they won't grow a penis until the age of 12.
The interesting thing is that it seems not only their penis grows but also there is a change in behavior (quote from the article above):
A little girl named Carla is currently going through the same transformation, aged nine. Despite being brought up as a girl, his mother noticed that from the age of five he was more inclined towards the rough and tumble play of little boys. He has recently had his hair cut shirt after wearing plaits for years.
Also there are examples of transgender people who have gender dysphoria often describing themselves as a "woman who is lost in a man's body" or vice versa.
Is there any serious scientific research that proves / disprove these perceived differences in behavior?