David Reimer was born a male, but a botched circumcision destroyed his penis, and so a doctor (his name was John Money, and he was a terrible person) thought it was better to have David get a sex change operation, and so David was raised as a girl instead of having him live his life as male without a penis.

David ended up killing himself later on in his life mostly because of his traumatic childhood.

Here's a link to a Wikipedia page about it: https://en.wikipedia.org/wiki/David_Reimer

Here's a link to a documentary about it on YouTube: https://www.youtube.com/watch?v=MUTcwqR4Q4Y

Circumcision basically destroyed his life. The story is very sad.