Because PEOPLE DON'T HAVE "GENDER".
Sheesh.
People, the word you want is "sex". Why is it so hard to get people to say sex when they mean sex? Why do people so readily give themselves to the ideology-driven corruption of language?
Whose side are you on, anyway?
Thank you! “Gender” is a grammatical term. Nouns have gender. People have sex, either male or female.