@Charlotte31,
Girls (children) that played like boys used to be called Tom Boys. Then, and even now, many parents raise a girl to eventually be a modern women. That means she plays with dolls, values non-roughhouse play, and bonds with other girls predominantly. Similarly, many parents, then and now, raise a boy to eventually be a modern male. That means he plays with trucks, might engage in roughhouse play, and bonds with other boys predominantly.
If we were so unisexual, we would see many girls on skateboards. Oddly, in NYC, I rarely see a young lady on a skateboard. Perhaps, she realizes that it will one day be hard to get a date if her limbs don't function that well, as an older teenager, due to a skateboard accident?
We have a sexual division in society, possibly reflecting the hope of parents for their boy or girl to one day take on a role that makes them grandparents of biological grandchildren?
I do not see many mothers or fathers not soothing a little girl's crying, due to a scraped knee. While these same parents might tell a son to stop crying, since it does not hurt that much.
I think we are stuck with gender roles, and to thwart that fact, with a child, is just possibly planting the seed of making a child a misfit amongst his or her peers.
Thank goodness we do not have to draft women into the military, like a particular country in the Middle East, due to the possibility of an existential war in the future. Meaning, isn't it nice that we have the luxery to have many men enjoy the world of men, and women enjoy the world of women, starting in childhood, even if some men like to knit, and some women like to play softball? But, it is not mandatory, and that is the beauty of our society.
P.S. I have read that the current American Psychological Association's DSM-IV (Diagnostic and Statistical Manual that defines all syndromes) only designates homosexuality as "gender confusion." The old pejorative definition of homosexuality is gone, but note that gender confusion is still thought of as a reality that can color one's life obviously quite well.