Child abuse is easy to get away with, especially if you're the parent/guardian.
Generally they can't do anything even if a third party knows and reports it. The statute of limitations is 7 years, so as long as they don't report it by the time they're 22 (and at that age they often still need you to cosign their student loans) you're scott free for anything you did to them when they were 14 or younger. Generally testimony by children 14 and younger isn't considered credible, and they are easy to intimidate out of testifying. (Just threaten to kill the pets, and kill a couple in front of them just as an example.)