The only thing I want to add is the other end of the equation, that some of them are effeminate men or women with masculine personalities, in addition to being autistic. That's why they don't fit in. Their autism that forces them to logically categorize everything into boxes makes them unable to accept that those characteristics, whether social constructs or not, do not mean they are somehow abnormal or not the correct sex. "I act and think like a man, I must be a man." - That wouldn't happen though unless society enabled it. They killed the tomboy.

There are also those with various other clustered mental illnesses, sexual fetishes, or who act a certain way to get attention or gain social advantage. (I don't believe for a moment that all the dudes in women's sports actually think they are women.)