Do opposites really attract in relationships?

From rom-coms to romance novels, there's a common trope when it comes to love: opposites attract.

But is that really true? Actually, it's the opposite in real life: A slew of research over the past several decades has shown that people tend to date people who are more similar to themselves. People with shared traits are also more likely to have the long-term attraction needed for lasting relationships.

"When people talk about opposites attracting, that's thought of as being, 'Oh, I know this one couple; they got together, and they don't have a lot in common.' But it tends to be the exception to the rule," Erica Slotter , a psychologist at Villanova University in Pennsylvania, told Live Science. "Similarity is still a robust predictor of attraction."

In fact, similarity plays a key role in all stages of relationship formation. Researchers look into a person's stated preferences, or the attributes people say they look for in another person.

"Most of the time, people say they want people who are like them," Slotter said. This holds for all sorts of attributes, such as socioeconomic status, religion, political orientation and hobbies.

When looking at the data on people in longer term relationships, similarity also seems to reign supreme. Tanya Horwitz , a researcher at the University of Colorado Boulder, led a study on these trends by analyzing past literature and large-scale demographic datasets. The results, published in the journal Nature Human Behaviour in 2023, concluded that up to 89% of traits between partners were positively correlated, meaning if, say, one person exercised a lot, their partner was likely to as well. This held for politics, health habits, substance use and more. "We did the raw data analysis with the 133 traits," Horwitz said. "It was surprising just how uncommon it is to see a trend where people are less similar."

So does that mean you're destined for someone who is your carbon copy? Not exactly.

One trait that tends to be different between partners is how they take charge in social interactions, also known as social dominance. If both individuals in a pair are dominant, "they tend to butt heads," Slotter said. In contrast, two submissive, go-with-the-flow people may never deal with problems in a relationship. People with opposing social dominance tend to be happier than those with similar scores, Slotter added.

Two people who differ on paper may also be attracted to each other for another reason: chemistry. For instance, studies on speed dating have found that what we say we want in a partner doesn't always match up to who we're physically or emotionally attracted to. How this works is still a bit of a mystery. Slotter said that it’s partly because when we talk to someone face-to-face, we’re still looking for similarity but in a more holistic way. She added that increased holistic similarity is found to be linked to better romantic chemistry.

— Why do couples start to look like each other?

— Why do people have different personalities?

— Are humans limited to 150 friends?

Even if they start out fairly different, partners can become more similar over time — a phenomenon called convergence, Horwitz said. Spending time together can shift things such as habits and lifestyle. This can also increase attraction as a relationship grows, Horwitz added.

Finally, who we think we are and our impressions of our partner may also affect lasting attraction. For example, a 2000 study in the Journal of Experimental Social Psychology found that it didn't matter whether strangers or friends thought individuals in a couple were similar. Instead, fondness, as well as relationship satisfaction, depended on whether the people in the relationship thought their partner was similar to them.

"It's really about that … subjective judgment you make," Slotter said. "If you feel like this person is similar to you, go for it. Because … that seems to matter the most."