i went to give blood yesterday. in the initial screening process, there's a whole list of questions they ask to warrant against the possibility of infected blood.
"you're a female, right?"
"um...yes. i'm quite sure of that."
"have you always been a female?"
"we have to ask this question now. it's a new thing. have you always been a female?"
"well, save for that short stint following fertilization when i was a zygote, yes i've always been a female."
thank god being a smartass doesn't constitute rejection of blood donorship by the red cross.