I wouldn't say close define gender, but I would say society dictates what is appropriate for each gender to wear. I'm not saying a person should go to an interview underdressed, but if someone is wearing something appropriate for business formal, or business casual etc, but is discriminated against because they're wearing male or female clothing that doesn't suit their biological sex, that is bigotry.
Now we could drill down on this concept, as to whether non trans people should be allowed to dress in skirts etc, since conventions in style are silly anyway, and skirts aren't inherently more female, and ties aren't inherently more male.
Those are fair questions to raise, and we should. Ties are stupid and hurt your eyesight long term.
I used a dress as a placeholder for, styling and presenting oneself as female when male or vise versa. Obviously a Hillary Clinton pants suit might be a more likely outfit to wear to something businesslike.