Good, Bad or Deficent?

Are young people born or brought up to be good or bad? Is it NATURE or NURTURE? Why do two people, even twins, who can be brought up similarly, turn out so differently? Why does Japan have the lowest murder and suicide rates? Can it be, as stated in the Guardian, in some cases attributed to diet? We know that it can affect behaviour - my brother gets hyper when he has artificial colours, people are intolerant to different foods for different reasons...can Omega 3 be a key element in our behaviour, is it the natural version of Ritolin & Prozac combined to trigger the more positive emotions?