A social experiment I saw the BBC`s child of our time episode where they put 2 twins brothers separatly into a play room with hidden camera. It was filled with a mix of all kinds of toys. One brother went and trashed everything, and threw the doll out of its cot etc. They put another boy in with him the the testosterone kicked in and he got even more bolshy.
The other twin when in the room alone played with a bit of everything and from memory was mostly interested in the kitchen/stove toys and caring for the doll. When they put another male child in with him he tried to get them to play with that game too, but they were not so inetrested and led him to a truck set or something similar, which the twin after some slight reluctance agreed to play with too.

The twins parents hadnt put them in childcare etc either I dont think. They had been in the same womb, same time, same toys and same treatment.