Age really has nothing to do with it, How much you want to bet the first time she smoked it was with a classmate from school. MJ is a weed that grows wild, it occurs naturally in nature.Some kids go hunting mushrooms at that age to get high. Some sneak into their parents liqueur cabinet when they are not home. It is like saying to prevent suicide we have to make all guns and sharp objects illegal.
No, it is not the same thing at all. Possessing a knife or a gun does not tamper with the chemicals in your brain. It has no direct effect on your decision making processes.
Another lame excuse from the deluded pot heads. Just because something is natural doesn't mean it is harmless. There are many harmful things in nature, some deadly.