As a psych grad student (albeit not one who specializes in paraphilias), I'd just like to chime in here and clarify a couple of things, as it looks like there's a debate brewing.

Pedophilia and child molestation are not the same thing. Pedophilia is the sexual attraction to children aged 11 and under, while child molestation is the sexual abuse of a minor. There are pedophiles who have never abused kids, although it's very difficult to get a count because of social taboos, and there are child molestors who wouldn't qualify as pedophiles (particularly in incidents involving pubescent children).

Mounting evidence seems to indicate that pedophilia is primarily caused by varying hormone levels that affect fetal neurodevelopment. This is similar to proposed causes for homosexuality, but this is not an attempt to excuse pedophilia. It's merely to clarify that pedophilia could be viewed as a sexuality, although obviously one that can never be acted upon. With that said, sexuality and paraphilias are very complicated and can be influenced by many factors.

The general consensus among psychologists, as far as I know, is that having experienced childhood abuse is NOT a notable or significant cause of pedophilia, but that it IS a predictive factor in child molestation. That's to say that someone who was formerly abused is more likely to have lower impulse control and give in to urges more easily, or to incorrectly view these types of interactions as "normal".

It's important to recognize that it's a clear minority of child sex abuse victims who go on to become abusers. Being more likely to go on to molest children than someone in the general population is obviously not a guarantee of anything.