"What is the cause of sexual abuse in the Catholic Church? Why are there pedophile priests in the Roman Catholic Church?"

In recent years, hundreds, if not thousands, of individuals have come forward claiming sexual abuse from priests in the Roman Catholic Church. Numerous "pedophile priests" have been identified. Sadly, rather than defrocking the priests (removing from the priesthood), the Catholic Church has in most instances attempted to cover up the sexual abuse by transferring the offending priest(s) to different parishes. 
The scandal and attempted cover-up continues to expand, reaching all the way to the papacy itself. So, what is the cause of sexual abuse in the Catholic Church? Why does pedophilia seem to be such a common problem among Roman Catholic priests?

http://www.gotquestions.org/Catholic-abuse.html