The scientists explained that the low-expression of the gene MAOA (monoamine oxidase A) is linked to higher levels of happiness in adult females. They added that they were not able to find such an association in men.
Lead author, Henian Chen, MD, PhD, said:
"This is the first happiness gene for women. I was surprised by the result, because low expression of MAOA has been related to some negative outcomes like alcoholism, aggressiveness and antisocial behavior. It's even called the warrior gene by some scientists, but, at least for women, our study points to a brighter side of this gene."
Even though females experience higher incidences of anxiety and mood disorder, overall, they tend to report greater happiness compared to men. Nobody has really understood why this is so. Chen believes this new finding might help explain the difference between men and women, and provide a deeper understanding of how specific genes affect happiness.
The MAOA gene targets the enzyme that breaks down the same neurotransmitters that many antidepressants target, namely serotonin and dopamine (plus some others). Serotonin and dopamine are sometimes called "feel good" chemicals.
Chen and team gathered and studied data on 193 women and 152 men. They had all taken part in a longitudinal mental health study called "Children in the Community". Their DNA had been analyzed for MAOA gene variation. A widely used validated scale was used for self-reported happiness scores.
They found that women with the low-expression type of MAOA were much happier than women with no such copies. Women with one copy scored higher, and those with two copies higher still.
A similar proportion of males had the low-expression type of MAOA, however, they did not report any higher happiness levels compared to the other men. Put simply, the gene does not make men happier.
Why does this happiness gene affect women but not men?Women have much lower testosterone levels than men. Possibly, higher testosterone levels found in men neutralize the happiness effects of MAOA, Chen and team suggest.
We do not know whether MAOA has an effect on boys, which then wanes as their testosterone levels rise when they get older. Chen said "Maybe men are happier before adolescence because their testosterone levels are lower."
Previous studies have shown that genetic factors are probably responsible for between 35% and 50% of the variations in people's happiness. It is important to pursue further studies to find out which specific genes impact on resilience and subjective well-being, Chen stressed.
Our individual well-being and happiness are not decided by a just a single gene, and not even by a set of genes, but probably by a combination of a set of genes combined with life experiences.
"I think the time is right for more genetic studies that focus on well-being and happiness. Certainly it could be argued that how well-being is enhanced deserves at least as much attention as how (mental) disorders arise; however, such knowledge remains limited."