A small percentage of every human population is born with sociopathic tendencies. A sociopath has no conscience, is incapable of love, and craves power. Good parenting and therapy may allow some to grow up to be "high-functioning" sociopaths, who lead relatively normal lives without harming others. Most, however, with or without good parenting, become career criminals. A very interesting finding is that nearly all cult leaders are sociopaths.
We're not born tabula rasa. Our genetic code starts at conception and is modified by the environment as we grow. Good parenting would make a huge difference, but it's not the single "law" that would create a better society.