I have a question

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3. Actual biological gender is more complicated than a female/male binary distinction

There are children born with genitals that are not distinctly male or female.

There are people who are born with XY chromosomes, but still develop female characteristics due to other biological factors suppressing their response to testosterone.

There are anatomical differences between "typical" male and female brains, but people whose brain anatomy is more like that of the opposite gender than their chromosomes would seem to indicate.

Gender is also, of course, about more than anatomy and genetics, but cultural norms and socialization. There's no particular reason to expect peoples' personalities to fall into line with often rigid stereotypes associated with gender.