Old enough so that converting them might be to hard if they were raised in the cult which is very likely. Why risk these teens being hidden followers like Children of the Corn I would be moving to just eliminate any risk. But ones young enough say to young to be educated in a cult should be taken care of with re-education. But if they are ages around the tweens send them to another location far away from the coast and any likely value to the enemy cult.<br/><br/>But no not magic brainwashing - like many faiths children raised in a cult and indoctrinated effectively would be solidly a risk. So I would think anyone a teen is a good cut-off point.<br/>>:)