It's hard to argue with science. And yet so many people keep trying.
The teacher began by explaining the many different ways nature can determine sex and gender beyond X and Y chromosomes.
"First of all, in a sexual species, you can have females be XX and males be X (insects)," the teacher wrote in her post. "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 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.)"
You may have noticed that, up to this point, Ann hasn't mentioned humans, something the teacher anticipated. She pivoted her argument to discuss the nuanced ways humans express sex and gender. (Mic did not independently verify the information in this post.)
"Oh, did you mean humans? Oh ok then. You can be male because you were born female, but you have 5-alpha reductase deficiency and 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 and 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, and 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 so 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 at all. And you can be male because you have two X chromosomes, but your heart and brain are male. And vice — effing — versa."
Ann ended her post with a very simple declaration.
"Don't use science to justify your bigotry," she said. "The world is way too weird for that shit."
As of Saturday afternoon, her post, which she published Thursday, has gotten an astounding 24,000 shares and over 1,800 comments.
As is wont to happen on the internet, a few trolls have descended upon the post, and a thread on Reddit's transphobic Gender Critical subreddit has popped up. But on Facebook, most people expressed gratitude for the knowledge.
Transgender people face harsh societal and legal discrimination just for being who they are. In the first two months of 2017, seven transgender women of color were killed. Whether a transgender person can use the restroom that matches their gender identity continues to dominate the efforts of state legislatures, even making its way to the Supreme Court.
Ann's reminder of the great diversity that exists in sex and gender when you adopt a biological lens is also a reminder of just how baseless the discrimination trans people face really is.