> I also wonder why Edith felt the need to mention gender not being binary in a discussion partly about whether biological sex influences choice of job, considering the fact that as far as I know biological sex is indeed binary, you either have at least one Y chromosome or you don't.
I think she refers that gender is not binary as you can be straight male, straight female, gay male, gay female, bisexual, asexual, etc.
I am not completely sure but I think there can be mutations where you have 2 chromosomes X and 1 Y. So XXY [1]