Um. Because sexism is prejudice against women. That's... actually what the word means.
I don't even know what you mean by "gender stereotypes that aren't particular to sex." I don't know any gender or sex related stereotypes that aren't based in sexism.
no subject
I don't even know what you mean by "gender stereotypes that aren't particular to sex." I don't know any gender or sex related stereotypes that aren't based in sexism.