Nature vs. Nurture plays a big part in this in my mind. If you grow up in a hostile environment, it is possible that you will lead a negative, and possibly violent life. Ex: Hitler
HOWEVER, there are persons who pull themselves out of hostile environments to live extraordinary lives.
Now does this mean that some people may actually be born evil, regardless of the nurturing they receive? Some philosophists do believe this point, and it may be true in some cases. I know kids who have the nicest parents, but they are just pure evil. Did something else, like a bully, trigger this evil behavior? This may also be true.
Does society cause evil? Can we blame society, like death metal and movies, for making kids evil? Or horribly depressed? One quote from a book reminds me of this fact. It's from High Fidelity, written by Nicholas Hornby.
What came first?Although this is a good point, no one can actually pinpoint what makes serial killers, and what makes people so depressed that they don't want to live anymore. Even though the situations and behaviors are various, I still believe, like Rousseau, that people are born good. They are born to be parts of society without causing trouble, and are 'forced' into a society built upon competition and values.
The music or the misery?
People worry about kids playing with guns or watching violent videos, that some sort of culture of violence will take them over. Nobody worries about kids listening to thousands, literally thousands, of songs about heartbreak, rejection, pain, misery and loss.
Did I listen to pop music because I was miserable, or am I miserable because I listen to pop music?