People's Niceness May Reside in Their Genes

A new study by two universities in the United States have identified receptor genes that have been linked to niceness in humans. Previous studies have shown that oxytocin and vassopressin make people nicer in close relationships. The goal of this experiment was to survey attitudes of a variety of people on things like civic duty and charitable activities and connect these results with hormone levels. Some were shown to have "nicer" versions of the genes that allowed them to overcome feelings of the world being threatening and help other people in spite of those fears. In the end, genes predicted behavior in combination with experiences and feelings.

http://www.sciencedaily.com/releases/2012/04/120410093151.htm