(The gene, called MAOA, affects the levels of feel-good chemicals in the brain, and comes in two varieties, a highly active and a less active type. Women with the less active type were happier than others, and those with two copies of the ‘happy’ type of MAOA were the happiest. However even though many of the men in the study carried the gene they were no happier than others and this could be because its effects are cancelled out by testosterone. I always knew testosterone was a poison.)
Source: Daily Mail