If it looks like a duck, walks like a duck, and talks like a duck...it's a duck.
Substitute woman for duck, and one has illuminating insight as to what our culture finds appropriate femaleness, as well as the absence of wiggle room.
Just ask South African athlete Caster Semenya. Muscular body? Deep voice? Stellar athletic performance? Must be a man.
Top it off, Semenya now needs to take a "gender verification test."
News flash: gender is not a more sophisticated or politically correct term for sex. Sex refers to chromosomes and genitals, and gender refers to social performance. Therefore, a person whose biological sex is male may have a female gender performance.
This brings about another issue: how do members of trans communities participate in sports teams? I will guest post this on the Trans Blog Group and hopefully get some feedback.