Hmm... having looked up the definition of ephemeral, I don't think I meant ephemeral. I meant based more on the social aspects or a feeling of gender

> I usually think of it as mutable

I have increasingly come to think of it multi-dimensional (e.g. one can have physical sex, feelings of gender, norm conformity, political gender, etc, etc) all existing independently of one another. Whether those are mutable (and who has the power to mutate them) depends on the dimension.