An interesting article from CNN is about bullying - but not from the perspective we're used to.
This piece was about the bully, not the bullied.
(Personal aside: I don't know how I feel about the "he/his/him" pronoun being used in this piece, though. It has male-oriented undertones... and females are definitely capable of committing serious acts against others. Even attempting to search for a female bullying image produces a female whispering, r one crying with grief. She is almost never the overt, physical perpetrator. Gender bias, much?)
However, similar to its coverage of kids and racial bias/ judgement, parents may be appalled to learn that their children are developing negative attitudes towards other people before they've even experienced enough of life to know what it means.
Personally, I don't think enough is being done to combat the issues that are right under parent's noses. If you child is displaying aggression within the home, with you, do you honestly think that will end when they walk out of the door, Spiderman backpack on, and bagged lunch in hand? If your little girl slaps you every time you tell her no, perhaps you should think about the way she will handle someone taking away her legos during play time.
So, when the problem becomes apparent, it is a parent's job to take action. Don't ignore a child's aggression! What guilt must emerge when you find out that Jack's bowl cut was converted to a buzz cut when your child planted the gum in his hair. Of course, your child has a mind of his/her own, and her decisions are going to be made independent of you. But the ability to hone their thought process and develop ways to handle anger, and implement consequences when boundaries are crossed are a parents job. So be alert, mom and dad. I have half a mind to say that you're as responsible as Billy is.