Biologically speaking, there are a tiny fraction of people that are born with indeterminate, or even both sets of external genitalia. There are also internal disconformities with external genitalia, and there are certain to be those born with genetic behavioural dysphoria. These folks have real issues they need to resolve as they see fit.

The number of people born with these medical issues is extremely low, but may be increasing due to endocrine disrupting chemical exposure in the womb and after. However, it's still a very small number of people.

Thanks!