I was speaking to my dh about the prison experiment just the other night. It was in regard to something else, but it really makes sense with authoritarian parenting styles, too. Parents take the God-given authority over their children, and begin to wield it negatively and lord it over them. Because the parent knows that the authority was given legitimately, they don't see their actions as wrong -- and the further you go with it, the more warped and wrapped up in it you become. You literally can't see it as wrong.
Thanks for sharing that article, it had some good insights into the psychological elements of this kind of abuse.