No good; those are based on nothing more than a cursory inspection of a baby's genitalia, and we already have a word for people whose sexual attraction is based on looking at baby genitals. No, biological sex is all about the number and size of your gametes. It's an unusual bodily characteristic to be attracted to, if only because gametes can't be observed with the naked eye, but if semen analysis and ovarian function tests are what gets your motor going, then who am I to judge?



(Yes, this also means that everyone who's sterile for any reason whatsoever is biologically sexless or "neuter", which is one of the reasons why we don't normally use biological sex to categorise humans, but how else is OP supposed to weed out the unattractive people?)