“I’m not a bigot, it’s just science that in a sexual species females have two X chromosomes and males have an X and a Y.”

To which a science teacher responded:

“First of all, in a sexual species you can have females be XX and males be X (insects), you can have females be ZW and males be ZZ (birds), you can have females be females because they developed in a warm environment and males be males because they developed in a cool environment (reptiles), you can have females be females because they lost a penis sword fighting contest (some flatworms), you can have males be males because they were born female but changed sexes because the only male in their group died (parrotfish and clownfish), you can have some males look and act like females because they are trying to get close enough to actual females to mate with them (cuttlefish, bluegills, others), or you can be one of thousands of sexes (slime mold, some mushrooms).

“Did you mean humans? Okay. You can be male because you were born female, but you have 5-alphareductase deficiency so you grew a penis at age 12. You can be female because you have an X and a Y chromosome but you are insensitive to androgens so you have a female body. You can be female because you have an X and a Y chromosome but your Y is missing the SRY gene so you have a female body. You can be male because you have two X chromosomes but one of your X’s has an SRY gene and you have a male body. You can be male because you have two X chromosomes but also a Y. You can be female because you have only one X chromosome. And you can be male because you have two X chromosomes but your heart and brain are male, or vice versa.

"I can add to that the chimera phenomenon. I know someone who is almost certainly a chimera as the result of being a twin, one of whom never got born but rather got absorbed into her. She was born hermaphroditic and her parents and the surgeon chose to render her male and raise her male, but she knows she is female and her twin was probably female. She knew she was female before she learned of the absorbed twin so the twin is explanation, not motivation. I’m sure this is rare but my friend cannot be the only instance of this phenomenon.

"Don’t use science to justify your bigotry; the world is too weird for that.”