Scientists believe they have identified the happy gene that makes us look on the bright side of life.
The researchers have found evidence that part of our DNA makes us either naturally positive or negative, reports express.co.uk.
The Essex University study looked at DNA samples of 100 volunteers and tested their responses to highly emotive images, using revolutionary computer therapy.
Scientists then measured how the volunteers’ genes transported the mood chemical serotonin around the body. People with short versions of the gene had stronger reactions, both positive and negative. But those volunteers with the long gene type expressed less reaction.
Elaine Fox, who led the study, said: "Those with the long version often fare best in fairly benign conditions. But they might not gain so much from a good experience."
"When times are really bad or really good, those with the highly reactive short genotype either go under or really benefit," she added.
It is hoped that identifying the gene will help treatment of depression and trauma.