Wouldn't castration serve the purpose better? (An eye for an eye and all that, you could forgo the pain relievers, though...if they withheld them from the child) Frankly, I'd argue that some twenty year old people aren't old enough to make such a life-changing decision, and I have the link to back it up. https://mentalhealthdaily.com/2015/02/18/at-what-age-is-the-brain-fully-developed/

Wouldn't castration serve the purpose better? (An eye for an eye and all that, you could forgo the pain relievers, though...)