at least over here in Germany it has been ruled that the parents can't be blamed for their children's internet use. If all else fails, blame it on the kids ;-)
Until what age would they be considered children for this ruling?
Presumably the legal age of responsibility, at which point they become responsible for their own actions.
I don't think this is sound logic. If you pay the electricity bill and then someone electrocutes you are you responsible for your own death? :-D