Its difficult to comprehend how an adult can sexually abuse a child, be it for CP or not. My guess is that most child molesters or producers of CP were sexually abused as children. If not then I am at a loss.
In that vein I looked up causes for people molesting children and found the following website.
Child Molestation Prevention
Its an interesting yet sad read.
Then check this out:
http://www.childmolestationvictim.com/statistics.html