This thread has made me realise that a lot of people wanted to reject being female rather than particularly wanting to be male.
So if there was a surgery and hormone free non binary option would you have taken it? Rather than a full on transition?
I think the point people are making is that we didn't conform to stereotypes. Society pushed the stereotypes to greater or lesser extents. And there was a lot of stereotype push and an individual happened to not want to go along with a lot of the stereotypes, some might well have taken the "change gender" option to fit in better. But actually they didn't have an issue with their gender, they had an issue with the gendered expectations, so when they grew up and had found niches they could follow their own interests without being constantly told they were doing their gender wrong, any interest in being the other sex went away. It's not being female we rejected, it's the gendered expectations themselves. (Hence: feminist.)
As an adult I'm quite happily able to be female and wear a mixture of clothes from the men's department and clothes from the women's department and ignore the hair-and-makeup-and-handbags thing and follow a mixture of interests with other people of either sex who share those interests. I think it's just easier to cross stereotypes as an adult. You have the confidence of knowing what you like, and you have more ability to surround yourself with like minded people. As a child doing similar things was much more judged and you may still be exploring what you like yourself.
For example if you're the only boy in the school who does ballet, you get grief; at ballet lessons much less so because you all have the shared interest; and if you go on to ballet school you're with a cohort of other young men all doing the same thing.
I think the pushing of stereotypes is much worse for kids these days too and that makes me sad. DD and I both had a short hair phase at around 4, no-one looked twice at mine, but DD got called a boy loads at preschool. DS got called a girl by classmates just for having a red coat. Not pink even, red.
Then there's the fact that puberty just isn't very attractive to any child. It isn't is it? I mean, growing boobs, you can no longer run around comfortably without finding and wearing a really good bra. Periods and all the hassle that comes with them. On the other hand hair everywhere and your voice going all weird and the embarrassment of wet dreams. Spots all round. Don't all children want to be Peter Pan?