[user104658]

There are three or at most four, not countless. Gender and sex are not the same thing, however, the concept of gender is rooted in the concept of male/female roles and character traits. So there can't be more than 4.

- Male
- Female
- "A-gendered" (i.e. not associating with either, showing no inclination towards aspects of either)

Then arguably

- "Changeable", which would be someone who adopts different gender characteristics dependent on the situation they're in at the time.


To be honest, I think the vast majority of people do fall into that last category though... And the ones who can't, it tends to because they're not massively comfortable / confident with their individuality, and thus feel inclined to cling hard to predefined character tropes.