[Puffer Fish]

There's a Dr. Seuss story that addresses transgenderism.

In the book "The Sneeches and Other Stories", there's a character who builds a machine that can transform the sneeches from one type to another, if they're not happy with the way they are.
The story later appeared in the animated series "Dr. Seuss on the Loose"

Sylvester McMonkey McBean appears and offers the Sneetches without stars the chance to have them with his Green Star-On machine, for three dollars. The treatment is instantly popular, but this upsets the original star-bellied Sneetches, as they are in danger of losing their special status. McBean then tells them about his Star-Off machine, costing ten dollars, and the Sneetches who originally had stars happily pay the money to have them removed in order to remain special. However, McBean does not share the prejudices of the Sneetches, and allows the recently starred Sneetches through this machine as well. Ultimately this escalates, with the Sneetches running from one machine to the next.
This continues until the Sneetches are broke and McBean departs a rich man, amused by their folly, and says to the audience "you can't teach a Sneetch". The narrator then comments that ultimately McBean was wrong, for the Sneeches soon learn that star bellies nor lack of stars cause inferior nor superior status, and they soon all live on the beach as one group.