That's the amazing thing about humanity. We're capable of such great feats of science, engineering, humanitarianism, but at the same time, we're capable of such despicable acts. I think the sad thing is most, if not all of us are capable of sinking to the depths of depravity, held back only by a flimsy, subjective moral code or fear of retribution, but it takes more than most of us have or are willing to give to rise up above the rest and become a shining example of humanity at its best.
Sadly, we have to take the good with the bad. Even if we do somehow manage to cure every insane criminal psychopath known to man and ensure that all children grow up in a loving, caring environment, you'll still have people who are perfectly sane, but make a conscious decision to go down the path others call Evil and you'll still have new sociopaths popping up every generation, due to mutation, defect or disease.
Of course, if we could round up these individuals, give them gun and drop them on the planets of alien fucksicles before they manage to get their invasion on, we'll be unstoppable.
