Similarly, though people living as men may have great differences in hormonal makeup, genital appearance, or even gonadal sex, they are all men for the purposes of gender. Of course, they still taste different. But the remarkable thing is that these unimpressive statistical differences between the sexes are transformed into an essential difference between the genders, so that there is a verbal sex and a mathematical one, and even Maria Mitchell was a member of the non-mathematical one. This is the magic of gender. Too often, people talk as if gender is imposed entirely from outside.
Sex exists in itself, and is sublimely indifferent to what humans think of it.
When we talk about gender as a set of social categories, it makes sense to talk about a finite number of genders. Here we can speak of doing gender, making gender. There's still something missing. Not every difference between people of different genders is meaningful. Some are arbitrary and go almost unnoticed.