That the guns would stop blazing if we stopped prescribing so much Ritalin. That the bloodletting would stop if we rounded up all the guns. The problem is that too many people want governmental edicts or prohibitions to do for their children what their parents did for them. It is understandably easier, more comfortable, for parents to see a child's misdeeds as the result of some negative influence from the outside, some Pied Piper of evil that he was powerless to resist. That allows parents room to hide from blame, an opportunity to divest themselves of the responsibility, to say it was out of their hands.
Children do make choices.
But acknowledging that their children behaved badly because they chose to closes the door through which parents escape responsibility. It brings to question the foundation of values on which the child made those choices. That foundation is a structure for which the parent is the chief engineer. A child with a deeply grounded foundation is not a puppet to outside influences. A child who grasps the wonder of life and understands that each living thing represents a network of lives and histories is not likely to choose killing as an appropriate response to conflict.