I agree with this. Not only that, but isn't the whole reason game ratings are on the games, so that parents can know the intended audience for the game without knowing about it?

It's the parents responsibility. Plain and simple.

More than likely if the parents don't care if the children play it, odds are they're not doing a lot of things as a parent. It's not the responsibility of the government to become parents. Look at the mess they've made trying to do that with other things that obviously don't work, the drug war for instance.