People’s long-term satisfaction with their lives often parallels that of their spouse, says a University of Toronto researcher in a study that deals a blow to theories that individual happiness depends mainly on genetic disposition.

Ulrich Schimmack of the University of Toronto at Mississauga’s psychology department and Richard Lucas of the University of Michigan studied the similarity in life satisfaction of more than 800 German married couples. They found that individuals’ reports of increased or decreased life satisfaction closely matched those of their spouses over a period of 21 years. The study is based on annual assessments of satisfaction in more than 10,000 households and will soon appear in the first issue of The Journal of Applied Social Science Studies (Schmollers Jahrbuch).

Results show that spouses are similar in all three components of life satisfaction – in the high variable component where satisfaction changes from year to year, in the changing component that produces gradual changes over time and in the stable component that does not change over long time intervals.

“Recent research has proposed that individual differences in overall happiness are largely determined by an internal set-point that people return to after being influenced by outside circumstances,” explained Schimmack. “But this research suggests external determinants of life satisfaction are more powerful than previously thought.”

“If we still hold to the theory that genetics account for an individual’s happiness ‘norm,’” he said, “then these results challenge behaviour genetics assumptions that assume we mate randomly and imply that people somehow manage to pick spouses that are highly genetically similar to themselves.”

This article was written from a news release by University of Toronto.