Scientists have for the first time discovered a 'happiness gene', which works by regulating the transport of serotonin in the brain.
It forms the first direct link between a specific genetic condition and a person’s happiness, as measured by their satisfaction with life.
Behavioural economist Jan-Emmanuel De Neve of the London School of Economics and Political Science (LSE) examined genetic data from more than 2,500 participants in the US National Longitudinal Study of Adolescent Health, examining which functional variant of the 5-HTT gene they possessed.
This gene helps control serotonin transporters in neuron cell walls, and has a variation, or allele, which can be either long or short. The long version is more efficient, resulting in more serotonin transporters in the cell membrane.
The team asked subjects how satisfied they were with theirlife as a whole. There were five possible answers: very satisfied, satisfied, dissatisfied, very dissatisfied or none of the above.
The results showed that nearly 70 percent of those with the efficient (long-long) version of the gene were either very satisfied or satisfied with their life – compared to just 19 per cent for those with the less efficient short-short form.
Conversely, 26 per cent of those with the short-short allele were dissatisfied, compared with only 20 per cent of those with the long-long variant.
Even possessing one long allele increased the likelihood of being very satisfied with life by 8.5 per cent, the team found.
"It has long been suspected that this gene plays a role in mental health but this is the first study to show that it is instrumental in shaping our individual happiness levels," says De Neve.
“The results of our study suggest a strong link between happiness and this functional variation in the 5-HTT gene."
He points out that other genes - as well as one's life experiences - also influence a person's happiness levels. But, he says, "This finding helps to explain why we each have a unique baseline level of happiness and why some people tend to be naturally happier than others."