Born to Be Blue?

Are you a happy-go-lucky person? Or are you more of a glass-half-empty sort? Turns out the answer might have been predetermined by your genes. A study of twins by U.K. researchers in the journal Psychological Science suggests DNA accounts for 50% of the variation in people's level of happiness as determined through such genetically driven personality traits as being sociable and active. Another study in the journal Social Science & Medicine hints at a global genetic link between happiness and age. According to the 30-year study of 2 million people in more than 70 countries, adults tended to report that happiness declined through their 30s and early 40s until it reached a 'nadir' at about age 44, then it began to rebound in older age'so long as severe health problems were not present. The drop-off was unrelated to nationality, income, marital status, education, or having children, leading the researchers to believe that humans are programmed to experience a so-called 'midlife crisis' and a decline in satisfaction with their lives.