Spouses do not grow more alike, study finds

Instead, people tend to pick their spouse based on shared personality traits, the researchers report in the latest issue of the journal Personality and Individual Differences.

"Existing research shows that spouses are more similar than random people," said Mikhila Humbad, lead investigator. "This could reflect spouses' influence on each other over time, or this could be what attracted them to each other in the first place. Our goal in conducting this study was to help resolve this debate."

The researchers analyzed the data of 1,296 married couples, one of the largest such studies to date, said Humbad, MSU doctoral candidate in clinical psychology. The data came from the Minnesota Center for Twin and Family Research.

The researchers wanted to know if husbands and wives become more similar as the marriage progressed. They examined a host of personality characteristics and found that, in most cases, the couples did not become more alike with more years of marriage.

The conclusion: Spousal similarity is better explained by selection than gradual convergence.

The one exception to this pattern was aggression. "It makes sense if you think about it," Humbad said. "If one person is violent, the other person may respond in a similar fashion and thus become more aggressive over time."

The research could have implications for future spouses as well as their offspring. "Marrying someone who's similar to you may increase the likelihood that you'll pass those traits on to your children," Humbad said.

The findings also come amid the backdrop of a booming matchmaking industry in which companies attempt to match people based on similar characteristics, she noted.

The research team also included M. Brent Donnellan and S. Alexandra Burt from the MSU Department of Psychology and William G. Iacono and Matthew McGue from the University of Minnesota.