I'm not sure how Steve was using the term, but "gender" isn't equivalent to "sex" in this sort of discussion.

"Sex" denotes biological differences, while "gender" denotes cultural conventions (which may or may not be directly related to biology).

Fallacy of begging the question.

"Gender" denotes the things which are not the physical genital apparatus, and includes but is not limited to types of behavior or preferences or tendencies toward behaviors or preferences. Whether all differences between the sexes in such areas are "cultural conventions" or whether some are in fact "wired in" at a non-cultural level is a topic of endless debate.

Indeed. I don't disagree with any of this. Perhaps I didn't phrase it well, but my parenthetical was intended to convey what you said in your comment.

You described gender as "cultural conventions". Which sort of assumes an answer to the nature/nurture debate; thus my reply.