How does a child learn to become a bully?

Bullying is mean and abusive verbal and physical behavior that is not acknowledged by parents, teachers and others who could stop it in its tracks. This would mean explaining the consequences to others early on and quiet time as a consequence. Half-hearted responses make it go "underground," that is, the bully becomes more sneaky and hurtful out of sight. Then, it is the victim who is blamed for being thin-skinned, or not understanding what the bully meant. I can see that the bully is working out some pain of insecurity and/or unhappiness, but that it is being expressed poorly. Teachers and school officials need to stand behind any findings of bullying and call the parents and child on any incident. Otherwise, they do learn that such behavior is without consequence.