Obviously, kids who commit dangerous crimes don't understand the consequences. Obviously, it seems the parents aren't doing a good enough job. Our children need to be taught not just that it isn't nice to bully or tease others. They need to be taught that this is a natural, albeit base, human tendency which must be actively counteracted. We must teach them to expect it, even in themselves, and fight it.
Human history is rife with models from which to learn and teach.
The natural sciences provide an almost limitless study area. We can make our world a kinder and gentler place if we teach our children to know the enemy, even when it is within themselves.