10, 13, and 17. The only one the required though was 17. If the child is old a mature enough, that would be the child's call. If the treatment is painful and the outcome doubtful, then letting the child opt out might be moral if the child is old enough to understand the decision.
If there is a god, I want to believe that there is a god. If there is not a god, I want to believe that there is no god.