Do married people’s personalities grow similar as they age together?
Conventional wisdom would say, yes. But that’s not what a new study by researchers at Michigan State University and the University of Minnesota has found. Except for one possible exception (aggression), any personality similarities exhibited by spouses are probably the same ones they had at the time they met, the researchers report.
In fact, those similarities may be what draws couples together — perhaps (from an evolutionary perspective) because it increases the likelihood that those traits will be passed on to future generations.
“We know that spouses have some similarity in personality. It’s not that strong overall, but it’s definitely there,” said Matthew McGue, one of the study’s authors and a professor of psychology at the U of M, in a phone interview. “From a psychological perspective, it’s interesting to know why that came to be.”
For the study, the researchers analyzed data of almost 1,300 married couples who have participated in other studies for the Minnesota Center for Twin and Family Research at the U of M. After examining a long list of personality characteristics (determined by the couples’ responses to the Multidimensional Personality Questionnaire), the researchers determined that the couples hadn’t grown more alike over time. Any spousal similarities, therefore, were better explained by selection than by “spousal convergence.”
The only significant exception was aggression. “It could be that over time mates begin to model the aggression of the people they’re living with,” said McGue.
Like previous studies, this one found that spousal similarities are low for broad personality traits (such as sociability), but high for value-related traits (such as those related to religion and lifestyle).
“One of the most interesting findings here is that, for the most part, spouses aren’t very similar in personality,” said McGue. “The one exception is the personality construct of traditionalism.”
It’s not unusual, he explained, for one spouse to be, say, an extrovert and the other an introvert. But it is unusual (or, at least, less likely) for one spouse to be politically conservative and the other politically liberal.
“Couples tend to be very similar on their underlying ideology,” he said.
“You can imagine why that needs to be the case,” McGue added. “One spouse can be very outgoing and the other very retiring and you can still have a very functioning family. But it would be very difficult to have a functioning family if they had different thoughts on how to raise kids. Will kids have a democratic say in the family, or will parents rule? Is religion important, or not?”
The study appears in the November issue of the journal Personality and Individual Differences. Its lead investigator was Mikhila Humbad, a doctoral candidate in clinical psychology at Michigan State.
Footnote: Couples may not grow alike in personality, but they may become similar in appearance, according to reports of a 2006 study. And the longer they’re together, the greater the similarities, apparently. Something, perhaps, to ponder over the dinner table tonight.
