I wanted to be a girl when I was a boy. I thought I should have been and it annoyed me that I was a boy. A lot of water has passed under a lot of bridges since, I'm a man now and I do reasonably well at it, and my adult perspective is that it's a shame we seem to want to fit children into neat boxes we're comfortable with, rather than letting them make their world how they see it. FWIW I'm ''non-binarian'', that's a term I've just made up, or maybe haven't, that fits me into another neat box suitable for public consumption. But He / Him / His are all fine because life's easier for me that way.
Anyway, my son's primary school has a mural on one wall that reads, All different, All equal. That's what we're teaching kids from the youngest age now as a basic principle of their society. Where does it end? I guess it ends in a place where a lot of grown ups feel a bit uncomfortable.