A couple years ago when I was training for America Ninja Warrior, I went to the home of a fellow contender who had built a course in his backyard and invited anyone in the area to practice and play and workout there (not just hopefuls, but anyone at all, most people were just there for fun and socializing).
He was ex-military, currently working as a stationary mechanic.
His two kids, a boy and a girl, were out playing in the yard (both too small to use the course).
I can't remember the context, but I said something about the daughter to him (maybe he was looking for her, and I said she had gone inside).
He mentioned he had two sons.
I just made a crazy assumption because he was wearing a pink Disney style princess dress! Well, I learned an important lesson about not making assumptions about people.
Our son is due in a few weeks, and we have mostly "boy" or neutral clothes, just because that's what we happen to have been given (big bags of hand-me-downs from family and clients), but some "girl" clothes mixed in too. We plan to try to be even. There is plenty of time for society to strengthen any natural tendencies toward self-gendering that may exist, there's no reason for us to make a point to accelerate the process.