In reply to:

sex was/is supposed to refer to the biological state of being male or female


The only problem with this being that a chappie called John Donne, nearly 400 years ago, wrote a poem called "The Good Morrow" (I may misremember the name - it's been a long time), in which the word 'sex' was used as a verb - to engage in coitus, or copulate, asyou might say. Ever since then, unfortunately, it has been difficult to use it in reference to the biological state on its own, since most people instantly associate it with the biological state of play!

cheer

the sunshine warrior