The odds that he was not molested himself as a child are slim to none.
Doesn't castration stop serial pedos? I don't even mean that in a torturous way. I would think that most of them would much prefer that to prison. Hell, if the one thing that turned me on was punishable by 100 years in jail, I'd want my own balls cut off. It would be freedom.
My junior high school had its own Jerry Sandusky. I always wondered why he seemed like he didn't like teaching. It turns out that he was just there to be around kids. He also bought the concession stand at the park where all the kids played in the summer. The boys he liked the most got a job with free candy. Luckily for me, he liked rich kids and my parents were poor. When he finally got caught, he ended up doing less than ten years in jail. His wife, who was his accomplice the entire time, got no punishment at all.
edit: I just looked him up on a sex offender web site. He still lives in the same town that he taught. His neighborhood is next to the high school. I don't want anyone to go murder him or anything, so I won't post his address, but here is his mug shot:
http://i186.photobucket.com/albums/x252/dotheopposite/tito.jpg