Bored teenagers

Nothing really. It shows that those three kids are murderers.
First off, you'd have to believe that boredom was those actual motive and not something they just said because they didn't want to explain themselves.
Secondly, you would need a much wider ranged correlation among teenagers committing murder out of boredom before deciding to pass judgment on an entire age group.

I can't really say what could've influenced them, but the way I see it, these kids are psychopaths, plain and simple. Normal people do not kill someone in cold blood just because they're bored. And contrary to what soccermoms, Jack Thompson, and other people say, I don't think violent TV/movies/video games had anything to do with what these kids did, I know many people who watch R-rated films and play violent video games that haven't committed a crime in their lives, I know someone who grew up on just G and PG filmes that broke into someone's house and got in a nasty fight with someone. I think these kids were probably like this for some time now or something happened to cause their lids to flip. They might have been abused or something, or they're just plain crazy. Either way, those kids are the only ones to blame for all of this.