This question is in effect asking “How do I mould and shape my child into a person who believes that individuals should be free from unwanted moulding and shaping by others?”
Paternalism is the idea that certain people or groups need to be controlled (in a benevolent fatherly way) for their own good.
A rule imposed on someone for the purpose of helping them to feel secure, is ludicrous. If I expressly don’t want something, yet it is imposed upon me anyway, how does that help me to feel secure? The opposite is the case.
Reason keeps a child safe because the child has the correct theory (that the stuff is dangerous); coercion is risky because the child’s theory is not based on the reality of the substance, but upon the possible punishment for an infringement of the parental rule.