In the early days of opera, womyn were not allowed to sing in public, not even in a chorus. How to fill in the female roles in opera? Pick a choir-boy with a great voice that has not yet deepened, by consent of their parents, perform a little operation on them, removing the testicles.
Results? Without the hormones needed for adulthood, their voices remained sopranos and altos while their chests and lungs matured regularly, their voices combined male power with female beauty. Now they were able to successfully pull off female roles onstage.
Today, this practice is illegal.
Farinelli was the most legendary castrato... history says these things, but can it make you believe them?