When David and Dana started dating, they were initially drawn to each other because of their stark differences in personality, interests, and hobbies. He was shy; she was outgoing. He was neat; she was messy. He was an omnivore; she was vegan. He liked classical music, while she preferred punk. At first, these differences seemed new and exciting. Their relationship truly seemed to exemplify the old adage that “opposites attract.” But over the months that they were together, these differences became obstacles, especially when it came to their differing views and values. Their relationship ultimately fizzled out.

The myth

It’s commonly believed that opposites attract. That is, that people are attracted to those who are very different from themselves with regard to qualities, experiences, and personality traits. It’s difficult to pinpoint the exact origins of the saying, although an early proponent of the theory was sociologist Robert Francis Winch, who studied couples back in the 1950s. His paper, “The Theory of Complementary Needs in Mate-Selection,” posited the idea that we are all searching for characteristics we lack and that an ideal couple is one in which their characteristics complement each other. Complementarity was believed to make a couple more interesting and to create a balanced relationship. For example, an introvert would choose a more extroverted mate, perhaps as a way for the introvert to benefit from the extrovert’s influence.

“Opposites attract” became a common expression and a trope in pop culture. Many people agree that the adage is true and can even point to an example in their own lives. Variety is the spice of life, as yet another saying goes, while our brains do love novelty. As we can see in the case of David and Dana, however, the idea that opposites always attract is just a romantic myth. The reality is quite different.

The science

An abundance of research reveals evidence for similarity attraction. We are typically drawn to people who are similar to us and attracted to those with whom we share interests and attributes. One recent study showed that, on average, partners share almost 90 percent of traits such as religiosity and political ideology, and even lifestyle factors, such as diet and whether or not they drink and smoke. The study participants were similar, down to drinking the same amount of water as their partner and spending the same amount of time on the computer. In general, they were similar in age, ethnicity, education, income level, and most importantly, they shared similar core beliefs and values.

According to various studies, not only are we drawn to people who are similar to us, but similarity is an indicator of the long-term success of a relationship. People who are similar tend to agree on more things, such as politics and religion, and to share the same communication preferences. In fact, there’s some evidence to suggest that opposites repel—particularly when it comes to views, values, and temperaments. It’s been shown, for example, that introverts and extroverts are less likely to pair up, busting the misconception that outgoing people and shrinking violets are attracted to one another.

Today, the online networks, sites, and apps that many of us use to find friends, dates, and love, all nudge us in the direction of people who appear to think in similar ways to us.

Opposites can attract

So, why is the outdated belief that opposites attract still so pervasive? This is because opposites certainly can be attracted to each other, but that attraction is often only short-lived, especially if the couple doesn’t share similar values. These kinds of relationships tend to be based on fleeting infatuation and physical chemistry, but they may not lead to love. Differences might make for an initial spark, although in the long term, similarities make for the most satisfying and lasting romantic relationships.