I said upthread something about our evolutionary past and as the years have gone by I have definitely shifted what I believe about differences between the sexes: I increasingly think that a lot of it is genetic (I was desperate to stay at home with my babies; DH didn't enjoy paternity leave...). That said, there is a bell curve of behaviour and a huge degree of overlap, and it drives me nuts to see young children forced into narrow parameters based on whether they are boys or girls.
Sending 6 year old girls to school in shoes they can't run in gives the girls a very clear message: appearance matters more than physical capacity or the freedom to make a choice, and the boys don't have to worry about this.
No wonder some of them at 10 are obsessed by hair, nails and sparkles. They've been told since infancy that this is what matters when you haven't got a willy, not racing around the playground making lots of noise and keeping fit.
Yes, it's okay to be interested in how your hair looks, and to do indoor activities that hone your fine motor skills, but to not be able to run around the playground is just bloody shocking when you stop and think about it.