The Myth of ‘Rubbing Off’ On Each Other: What Decades of Couples Research Found

We’ve all heard the saying that “opposites attract.” While that particular plotline works well in romantic comedies, in real life, people actually prefer relatability, seeking out partners with whom they share similar interests and personalities. This pattern even has a name—it is called assortative mating. 

Assortive mating has decades of research behind it, and it shows that people not only prefer partners who are like them, but have relationships that last longer with a similar half. It’s even been suggested that the longer people are together, the more alike they will become, getting closer and closer as each person’s personality “rubs off” on their partner.

This is an intriguing idea. And it certainly seems conceivable, as we know that people’s personalities can change and evolve for a variety of reasons. 

But is the “rubbing off effect” actually real? Studies have given us reasons to be skeptical, but the question is far from resolved.

A Closer Look at the Evidence

In 2008, German researchers published a study in the journal Personality and Individual Differences that seemed to offer evidence in favor of the rubbing-off effect. 

Nearly 7,000 German couples were recruited to take a Big Five test, with each partner given individual ratings for Extraversion, Agreeableness, Openness, Conscientiousness and Neuroticism.  When researchers compared the partners’ profiles, they found that those in the longest relationships were more likely to have matching levels of Openness, Conscientiousness and Agreeableness—which is exactly what the rubbing-off effect would predict. 

However, what the researchers didn’t have was a baseline measurement from before the couple started dating. It’s entirely possible that the partners with similar Big-Five trait levels had always been that way. To see if their personalities were really converging, the researchers would have to test again in a few years.

So they did. Around 4,800 couples from the original study agreed to take part in a follow-up study, retaking the test five years later. If the rubbing-off effect was real, individual partners should have grown more alike over that period.

They hadn't. Couples who'd been together longest were still the most likely to share personality traits, just as before—but that wasn't because they'd converged. When the researchers tracked each couple's scores over the five years, there was no sign that partners were becoming more similar to each other. The link between similarity and relationship length showed up only when comparing different couples at one point in time, not when following the same couples through time.

In other words, similar people seem to pair up and stay together in the first place, rather than becoming similar after the fact. The researchers concluded that personality compatibility is likely what brings people together and helps sustain the relationship, not a byproduct of it. No rubbing off required.

Other Factors Matter More Than Personality

Personality isn't the only thing couples have in common—and it's far from the biggest one.

A large 2023 study in Nature Human Behaviour pooled data from hundreds of previous studies and nearly 80,000 couples, comparing how alike partners tend to be across a wide range of characteristics, including personality, political views, religious beliefs, education, IQ and habits like smoking and drinking, among others. 

Personality made the list, but it wasn't near the top. Couples were far more likely to match on things like political views, religious beliefs, and education level than on any of the Big Five traits,  including Openness, which came out as the most “shared” personality trait of the bunch.

The takeaway: if you're looking for what really draws couples together and keeps them alike, personality is a minor part of the picture. Values, beliefs, and life circumstances matter more.

But Living Together Still Leaves a Mark

Belief and background may matter more than personality, but that doesn't mean personality is untouched by a long relationship.

A 2021 study in the Journals of Gerontology: Series B tracked nearly 4,000 older couples over eight years and found that partners' levels of Openness, Extraversion and Neuroticism tended to rise and fall together in response to changes in their fortunes, good or bad—as if shared life circumstances were nudging both partners' personalities in the same direction at once.

That might sound like proof of the rubbing-off effect. But the researchers offered a simpler explanation: couples who start out with similar personalities are also likely to respond to life's ups and downs in similar ways. Their traits move together not because one partner is rubbing off on the other, but because similar people react similarly to the same experiences.

Older research backs this up. A 1992 study followed roughly 300 couples over 20 years, from 1935 to 1955, and found no evidence that partners grew more alike as time passed—despite decades together.

Myth or Reality? The Jury is Still Out

The evidence so far doesn't support the rubbing-off effect, but that's not quite the same as proving it false.

As the researchers behind these studies point out, personality convergence in relationships has rarely been studied systematically. What data exists doesn't back the idea, but there isn't nearly enough of it to close the book. Different study designs might yet turn up real evidence that long-term partners grow more similar in personality the longer they stay together, a bit like how they pick up each other’s habits. 

One study, published in 2007 in the Journal of Personality and Social Psychology, may hint at why the effect has been so hard to detect. Researchers gave 172 newlywed couples a personality test shortly after their wedding, then again a year later. On average, partners' personalities had grown slightly more alike over that year—a small but real shift, and a contrast to older studies that found no such change over time. Interestingly, partners' emotional responses didn't converge the same way; only personality did.

The researchers have a theory: the early months of marriage might be a distinct window in which partners are still absorbing parts of each other, an effect that fades as the relationship settles into its longer-term rhythm. If that's right, it would explain why studies of couples five, ten, or fifteen years into the relationship keep missing the rubbing-off effect. By the time researchers start looking, any convergence happened long ago, and partners already look like they were always alike.

But this study was small—under 200 couples—and hasn't been confirmed by larger follow-up research. That's not enough to lift the rubbing-off effect out of “unproven.”

For now, the idea that partners grow more alike over time remains unconfirmed. If it's real, it's likely subtle, modest, and may apply to only some couples. Solid proof may never arrive—but the question is interesting enough that researchers probably won't stop asking it.