Its not the only defence, important and necessary, but also I think educating children about these risks in school is important (my kids' school does okay at this), and government regulation and criminalising such activity is useful too.

"Parenting" is a nebulous concept and at least to me, it also includes pushing for better laws for children. Nobody would think it's reasonable to allow stores to sell cigarettes to children and tell parents "if you don't like it, just don't let your kids smoke".