Sex preference is one thing, gender is something else . . .
Indeed. And biological sex is something else...
I've never had biological sex - is it legal? Please explain, with diagrams.
Are you sure? All humans, as I understand it, has a biological sex.
Having a serious discussions about this topic might transform into a political discussion, and should perhaps be avoided. The unserious part, I think, should be fine.
Have a bit more patience with newbies. Of course some of them act dumb -- they're often students, for heaven's sake. - Terry Pratchett