Two sets of the same gene, bestowed by both parents, make an individual doubly happy with his life, report behavioural economists at the London School of Economic and Political Science.
Jan-Emmanuel De Neve, the study's author, and his team questioned more than 2,500 people in the US about their level of happiness in life. At the same time, their DNA was analyzed to see if the gene, 5-HTT, had been duplicated or not.
5-HTT monitors nerve cells in managing serotonin, 'the happiness drug', a chemical produced in the brain and this determines mood. The 'long' 5-HTT gene leads to many serotonin transporters in neuron cell walls. The 'short' version only links with only a few.
When there are two sets of the gene inherited from both parents, it results in more serotonin in the brain. 69 per cent of people in the study, who had two copies of the gene said they were either satisfied or very satisfied 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 per cent with 19 per cent very satisfied and 19 per cent satisfied. In fact, people who had low levels of the chemical were more vulnerable to depression.
De Neve states that although there are other genes and factors behind a happy mood, these findings help 'to explain why we each have a unique baseline level of happiness and why some people tend to be naturally happier than others, and that's in no small part due to our individual genetic make-up.'