I don’t believe that gender even exists. Some people define woman as whoever identifies with that label and/or is treated as a woman societally and I think that is a functional definition.
Atlas moment
I actually tend to agree with the first sentence in that post. Creating an unnecessary distinction between gender and sex serves to create more confusion than not, and it's perfectly acceptable to talk about socially-constructed structures based around sex and/or masculine/feminine identity without deviating from sex. The terminological distinction only emerged with John Money (a problematical figure for many reasons), and even then only solidified with the emergence of feminist and "gender/queer" theory in the succeeded decades, which seems more indebted to ideology than to biology.