A friend forwarded an article from the Economist summarizing some evidence that happiness is genetic.

THE idea that the human personality is a blank slate, to be written upon only by experience, prevailed for most of the second half of the 20th century. Over the past two decades, however, that notion has been undermined. Studies comparing identical with non-identical twins have helped to establish the heritability of many aspects of behaviour, and examination of DNA has uncovered some of the genes responsible. Recent work on both these fronts suggests that happiness is highly heritable.

As any human being knows, many factors govern whether people are happy or unhappy. External circumstances are important: employed people are happier than unemployed ones and better-off people than poor ones. Age has a role, too: the young and the old are happier than the middle-aged. But personality is the single biggest determinant: extroverts are happier than introverts, and confident people happier than anxious ones.

Surely there is a strong genetic component to happiness. However, I’m mostly interested in the environmental components of happiness.

In my experience, people react negatively toward displays of unhappiness. This suggests that happiness signals something desirable about an individual, perhaps success or social status. If unhappy people are unsuccessful or undesirable, it’s best not to invest too heavily in them. If happiness didn’t signal, then why avoid unhappy people?

One problem with looking for simple genetic determinants of happiness: success and social status have genetic factors too. Twin studies won’t eliminate this complication, and I’m not sure how easy status should be to control for – status within a local social network, rather than within society, seems more likely to be important.