Is Our Happiness Preordained?

"In one study, researchers at the University of Edinburgh suggest that genes account for about 50% of the variation in people's levels of happiness — the underlying determinant being genetically determined personality traits, like "being sociable, active, stable, hardworking and conscientious," says co-author Timothy Bates. What's more, says Bates, these happiness traits generally come as a package, so that if you have one you're likely to have them all."

http://www.time.com/time/health/article/0,8599,1721954,00.html