It all started by changing a term denoting physical traits; i.e., sex, with a grammatical term, denoting linguistic differences; i.e., gender. One of the best illustrations of deconstructionism available.
I am not an English major but I know the difference between the words "sex" and "gender."
I really get perturbed when I see the term "gender" used when the correct word should be "sex."
Using the word "sex" now seems to be exclusively for the act of procreation and is almost taboo. I get tired of filling out forms that ask me my gender rather than my sex.