Why is any of that “natural” or “inevitable”? As a kid, I’ve never done any of that nor had any urge to. Certainly not as an adult.
I don’t think you understood what I meant, and I’m not talking about adults, but about little children. An example of crossing “gender” boundaries: a young boy might not know that the social directives for “masculinity” require him to act as if he’s indifferent to the suffering of others, or he might not have fully assimilated his role. He might start to cry in sympathy when a friend is hurt or unhappy.
As an example of confusion over biology, one of my sons used to refer to a time “when I was a girl,” by which he meant before his hair was cut. It was simply explained to him that he had always been a boy, and the length of his hair was not what determined this.