There are many misconceptions in this thread and comments.

Falsetto is the technique that men use to sing high. Prepubescent boys can sing soprano in their natural voice because children have very high voices.

Cutting off a prepubescent boy’s balls doesn’t make his voice higher, it just prevents him from ever going through puberty, therefore his voice never drops. He will keep his childhood vocal range for life.

Yes this was a real thing that was acutally done.