The gene, called 5-HTT, is responsible for how well nerve cells manage to distribute serotonin -- a chemical produced by the pineal gland in the brain which helps control mood, the Journal of Human Genetics reports.
People with low levels of serotonin, itself nicknamed the 'happiness drug', are known to be more prone to depression, the Telegraph reports.
Now behavioural economists at the London School of Economic and Political Science have found evidence that people with the 'functional' variant of the 5-HTT gene tend to lead happier lives.
Jan-Emmanuel De Neve and colleagues asked more than 2,500 people in the US about how satisfied they were with life, and also analysed their DNA for presence of the gene.
The 5-HTT gene provides the 'operating code' for transporting serotonin in neuron cell walls. The 'long' version of the gene leads to more serotonin transporters in these walls, the 'short' version less of them.
As we inherit a set of genes from both parents, the possible combinations of this are 'long-long', 'long-short' or 'short-short'.
The researchers found that 69 percent of people who had two copies of the gene said they were either satisfied (34) or very satisfied (35) with their life as a whole.
But among those who had no copy of the gene, the proportion who gave either of these answers was only 38 percent (19 percent 'very satisfied' and 19 percent 'satisfied').
De Neve, former Fulbright scholar at Harvard, said: '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.' IANS
