Quote Originally Posted by oskar View Post
You identify the gender of a person by the way they dress and behave.
This is completely and totally incorrect. How someone dresses and behaves has nothing to do with the gender they identify with.

Quote Originally Posted by oskar View Post
You'd use the one that's overtly obvious, and that one has nothing to do with the genitals or the chromosomes of that person.
Male and female are the two sexes, and those are determined by chromosomes. The personal, singular pronouns in the English language are used to identify male and female. The personal, singular pronouns in the English language are based on sex, not gender. Not one word of any of this is in dispute whatsoever.