Married couples tend to start off with similar traits, rather than their personality characteristics gravitating towards each other with time, researchers from Michigan State University found. The study, published in the journal Personality and Individual Differences discovered that individuals tend to select their spouses based on shared personality traits.

Personality was assessed using the Multidimensional Personality Questionnaire. The investigators evaluated whether similarity increased with time during a marriage.

Mikhila Humbad, lead investigator, said:

Existing research shows that spouses are more similar than random people. 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.

Humbad, MSU doctoral candidate in clinical psychology, and team examined the data of 1,296 married couples, from the Minnesota Center for Twin and Family Research. The investigators say theirs was one of the largest such studies ever made.

They wanted to find out whether husbands and wives eventually become more like each other as the marriage progressed. After assessing a wide range of personality characteristics, that found that couples generally did not tend to become more alike as the years of marriage progressed.

The researchers concluded:

Spousal similarity is better explained by selection than gradual convergence.

The researchers believe that their results suggest that selection processes are likely more important than spousal socialization processes for understanding the origins of spousal similarity in personality.

Aggression appeared to be the main exception. They found that an aggressive partner was more likely to pass on that trait to the other person.

Humbad said:

It makes sense if you think about it. If one person is violent, the other person may respond in a similar fashion and thus become more aggressive over time.

The authors say their study may have implications for future spouses as well as their children.

Humbad added:

Marrying someone who’s similar to you may increase the likelihood that you’ll pass those traits on to your children.

Their findings may also confirm current criteria used by the booming matchmaking (dating) industry, which usually tries to match people based on similar personality traits and interests.

Sources: Michigan State University, Personality and Individual Differences.

“Is spousal similarity for personality a matter of convergence or selection?”
Mikhila N. Humbad a,*, M. Brent Donnellan a, William G. Iacono b, Matthew McGue b, S. Alexandra Burt
Personality and Individual Differences (2010). doi:10.1016/j.paid.2010.07.010

Written by Christian Nordqvist