inherently evil?

Lately I have been focusing on an essay I am writing about child murderers, but as I work on it more and more I am finding my focus is shifting more to the lack of empathy and human emotion involved in each case. Anyone watching the news would have seen the story about the young girl that was gang raped outside of the high school homecoming dance. What is shocking most people about the case is the fact that at least twenty people were involved and watched as this girl was victimized again. My own reaction was less shock and more interesat in the fact that no one helped her. That they stood by and watched. The only reason it was reported was because another student overheard two people talking about it as they had seen it firsthand. This girl was left stripped and beaten under a bleacher for hours before police found her. What is it that triggers peoples' fascination in cruelty and violence?What is it that causes them not only to watch, but to just stand there and let it continue without helping the victim. This is not a new concept in any form, it has occured endless times throughout history. It seems that human beings have two impulses. The impulse of empathy and sympathy that we as a society hail as noble and esteemed. The other impulse is cruelty and a fascination with destruction. This impulse we tell ourselves is a representation of all that is wrong with society, but we seem to acknowledge it and try to curb it, but never focus on why it exists. Is is genetics that control it, environment? Are we only good and moral because others tell us to be? Are the true individuals the ones that accept the negative impulse and drive it to its extent and where religion and spirituality come into play. Are we naturally cruel and careless and the trial in religion is to fight against ourselves?