Some people are born happy, scientists say. Researchers have identified a "happiness gene" that makes people more likely to feel satisfied with their lives. Their sunny dispostion is an accident of birth, at least in part.
Those who carry the less efficient version of the gene are more likely to be pessimistic. Their tendency to see the glass half empty is equally a part of their inheritance.
The finding is the first to demonstrate a link between the gene, called 5-HTT, and satisfaction. People with the long version are more likely to be cheerful while sulkiness is the default position of those with the short version. Knowing which version of the gene they carry may help people improve their mood.
Jan-Emmanual De Neve, a behavioural economist at the London School of Economics, which led the study, said: "In five or 10 years, people will be able to read their genome. If you find you have a predisposition to see the glass as half empty then when you feel down, you may think 'Maybe my biology is fooling me into thinking my situation is less rosy than it is.' That combined with your own will power may help you get out of the psychological dip and go above and beyond. Knowledge is power."
The 5-HTT gene, which regulates the brain chemical serotonin, has been indirectly linked with happiness before. In research published in 2009, scientists showed that people with the long version of the gene had a subliminal tendency to avoid negative images and select positive ones. They concluded that the gene contributed to "attentional bias in the selection of emotional stimuli".
The new study, in the Journal of Human Genetics, goes further by linking the gene with life satisfaction, now recognised as fundamental to happiness. More than 2,500 adults in their twenties were asked how satisfied they were with their life. Those with two long versions of the gene were 17 per cent more likely to say they were very satisfied.