A single, hormone-delivery gene may determine whether a person is naturally happy or gloomy, say British researchers who conducted a series of psychological and genetic tests on 97 volunteers.
The results showed that participants with the long variant of the 5-HTTLPR gene paid attention to pleasant pictures and screened out distressing images, while those with a short variant of the gene had opposite preferences, Agence France Presse reported.
"The results indicated that a genetically driven tendency to look on the bright side of life is core cognitive mechanism underlying resilience to general life stress," wrote the University of Essex researchers.
The study appears in the journal Proceedings of the Royal Society B.
The 5-HTTLPR gene plays a key role in determining how the neurotransmitter serotonin functions within the brain. Serotonin transmits chemical messages between nerve cells and has been closely linked to mood, AFP reported.