I do not think there is much debate on this subject at all. Pretty much all the data on this area, from child workers, courts, and the police show that in the majority of cases of child molestation, it is a parent who is the perpetrator, and is committed within the family home.
I don't think that parents are the main cause of child molestation. This is because I believe it is usually extended family members or family friends that do such things. I think biologically people are normally turned off by their offspring, and this would limit such terrible events. People less direct in the blood line probably are more at fault.
Parents cannot be solely to blame for a child's molestation. It is often impossible to know who a molester is and they may seem like very trustworthy people. What a parent can do is ensure the child knows what is appropriate and what is not so the child will be sure to speak out if something is wrong.
I am sure there is a lot of cases where the parents molest their kids. I however think outside forces are a greater concern to children than parents. Most parents would never do such a thing to their own flesh and blood. You have all kinds of outside groups or people who have been caught molesting children, including the Catholic Church.
I do not think parents are the main cause of child molestation. I believe that sexual predators and pedophiles are the main cause of child molestation. Parents must do the best that they can to prevent their children from being molested, but ultimately the chance of a child being molested is fairly high considering that parents cannot always be around their kids especially when their kids are at school.