So, if you are correct, how, in the broadest way, should things change. At what age should people decide on their sex. How should society be organised.
The Government has learned to evolve to recognise and enfranchise minority groups: Females, Homosexuals, other ethnicities, disabled, young, etc.
Why shouldn't it learn to accommodate transgender people?
It's notable that male homosexuality was illegal, whereas female homosexuality was not.
The transgender argument has been firmly rooted towards ostracising transwomen, but transmen are rarely mentioned.
There seems to be a discrepancy in the equality of sexes in terms of the transgender and homosexiality aspects.
As far as the ages of children are concerned, I'm content to be led by the medical profession.
But you've missed the point. They aren't choosing their sex, they are choosing their gender. Their sex was assigned at birth.
How should society be organised? That's for another day.