Some people get more than good looks from their parents.
Those who had a variant in the gene that transports serotonin, were more likely to look on the bright side of things, researchers say.
Serotonin is a neurotransmitter that influences emotions and moods.
The study tracked people's reaction to positive and negative images. Those who had two short versions of the variant gene were less likely to notice the bad image.
This is the first time a genetic variation is linked with postive thinking, according to lead researcher, Elaine Fox.