In my mind it has to do with gametes. If an intersex person has functional ovaries that produce eggs that are fertilized with sperm, can carry the fetus to term and give birth- then they're closer to female

If they can do that, but also have functional testes that produce viable sperm, can get an errection and impregnate a partner then I'd still even count them closer to biologically female if they produce eggs- but accept that they're biologically perfectly intersex (and be highly impressed)

Though as far as I remember reading the production of one hormone can interfere with the others, and so chances of pregnancy are slim. I don't remember ever hearing of someone in the scenario above, tho .

Yes I do know about XXY (present as taller than average women), or XYY (men) and the XY males who present as female until they grow a penis at puberty (low testosterone that kicks in only as a teen). All of that is fascinating, and I don't dislike the variation in human beings! It's nature trying new things and that's neccessary for species to survive

(And I truly don't give a rats-ass how people identify. I'll call people whatever name they want, and refer to them in whichever way they want even in private conversations that don't include them. This is just how I'm currently categorizing biological sex in my own mind. There's plenty of room for re-interpretation and if new terms are decided upon I'm fine with aquiring and using them )