NICE people are born, not bred, according to researchers who claim that "selfish and tight-fisted" humans might be able to blame their genes.
The study found human kindness is not just evoked by good examples set by parents.
In fact, some people are born with generous genes that incline them towards niceness.
Previous studies have linked the hormones oxytocin and vasopressin to the way people treat each other, especially in close relationships.
Scientists already know oxytocin promotes maternal behaviour, with people exposed to the hormone in lab experiments demonstrating greater sociability.
Researchers at the University of Buffalo wanted to apply these previous findings to a larger scale to see if these chemicals promote other forms of nice behaviour, such as giving money to charity or being blunt likeMr Nasty Simon Cowell.
The "nice" hormones work by binding people's cells through receptors.
Certain genes determine how receptive people are to these hormones.
Participants were asked questions about their attitudes toward civic duty, such as whether people have a moral duty to report a crime, other people and whether the world is generally a good or bad place, and about their charitable activities, like giving blood or going to PTA meetings.
Of those surveyed, 711 people provided a sample of saliva for DNA analysis, that showed what form they had of the oxytocin and vasopressin receptors.
Results, published in the journal Psychological Science, showed people have "nice" versions of the genes, which when combined with the subjects' views on the world, make them more likely to help others.