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Opposites Similarities attract. In relationships, we tend to get along better with people like us—a whole lot of studies prove it. But there are lots of ways we can be like each other, and in romantic compatibility, some of those ways are more important than others. Researchers have tried to figure out what matters most. To check out your relationship checklist, click on the criteria.

But first, various disclaimers:

  • Shared traits and experiences can bring us together and help us navigate long-term relationships, according to research. This does not mean that partners who have less in common with each other are doomed. Many couples handle differences successfully. There’s also the question of how we define difference (for more on this, start clicking).
  • Our priorities vary according to what kind of relationship we’re looking for. If we’re looking for something brief, we won’t care that they want zero kids and we want six.
  • The research is based largely on heterosexual couples. The main conclusions apply to long-term same-sex relationships too, research suggests.

Do you both laugh at the same stuff?

What you say
Are you both laughing at (or scorning) the Judd Apatow movie? And does it matter? Yes. Students see sense of humor as the most important shared trait in relationships. In our survey, 67 percent of women and 62 percent of men said
this is “pretty important.”

What the research says   
Maybe. Shared humor seems important for compatibility. It might matter most to women who are evaluating men, according to a 2005 study: In heterosexual relationships, women want men who make them laugh, and men want women they can make laugh. (Beautiful symmetry there. The research doesn’t say how this plays out for gay couples.)

A skeleton walks into a juice bar: “I’ll have a smoothie. And a mop.”

Are you as smart and educated as they are? Should you care?

What you say
It depends on what we mean by brainpower. In our survey, only 18 percent of students considered an IQ match “pretty important.” Education level was rated higher. Twenty-five percent of students rated similar education level
as “pretty important” and 42 percent said it “seems to help.”

What the research says   
Science seems undecided on whether an intellectual match matters. But what if you’re getting a PhD and they’re not sure they want a degree? Matched education matters far more to us than it did to our grandparents, for whom sex roles were more traditional and defined. The trend for people of similar education levels to marry each other has increased economic inequality by 25 percent since 1960, according to a recent study.

Education level tends to correlate with our attitudes and life goals.
Again, it’s really about compatible goals and values.

They can’t get into Lorde. Deal-breaker?

What you say
Yes, music matters. In our survey, 21 percent said it’s “pretty important,” and a further 47 percent said it “seems to help.”

What the research says   
Yes. A 2006 study showed that college students socializing online asked about music preferences more often than all other conversation topics combined. That’s because music works pretty well as shorthand for our personality and values. When people share our music tastes, we like them more.

Here’s how music tastes influenced heterosexual attraction, according to a classic study (1989): (Note: These are not objective findings on musical genres.)

  • Heavy metal: Makes men more attractive, women less attractive*
  • Classical: Makes women more attractive, men less attractive
  • Country: Makes all of us less attractive

* The late 1980s were the era of heavy metal. Don’t expect the same effect today.

How well do your music tastes reflect your personality? Take the quiz.

Opposites attract: Yes or no?

What the folklore says             
We like the idea that opposites attract and help us meet each other’s needs. In a 2008 study of college-educated adults who were using a dating website, 86 percent said they wanted a complementary (different) partner rather than a similar one.

What the research says   
Not so much. In fact, we tend to choose partners like us—people we consider similarly attractive, who have compatible values, and who share certain characteristics, experiences, and even genes. This conclusion is based on decades of research and applies to long-term gay relationships too.

In a recent study of people using the dating website eHarmony, “of the 102 traits in the data set, there was not one for which women were more likely to contact men with opposite traits,” wrote researcher Emma Pierson in FiveThirtyEight this year. “Men were a little more open-minded.”

When both partners are OK with traditional gender roles, opposites can be more easily accommodated (because different education levels don’t matter so much). Science has also identified the following opposite pairings that seem to work:

  • Night person + morning person
  • Person who attracts mosquitoes + person who doesn’t
  • Person with a good sense of direction + directionally challenged person

These three are brought to us by 23andMe, a website covering genetics research.

Can a (social) butterfly land on a wallflower?

Here’s what we mean by personality: Introvert or extrovert?
Conscientious or sloppy? Agreeable or grouchy? That sort of thing.

What you say
Maybe. One in three of our survey respondents said matching personality traits are “pretty important.”

What the research says   
Maybe. Matching personality traits appear to be less important than some of the other stuff—at least initially. That might be a good thing: “[P]eople seem to want to find partners whose personalities are similar to theirs, but for some reason fail to do so,” according to a 2005 study. Apparently, there’s a gap between our perception and reality: If we like someone, we think their personality is closer to ours than it actually is. In long-term relationships, a personality match seems to matter more.

How partners interact with each other is vital—and probably more important than a personality match. Prioritize the personality traits that contribute to positive interaction: kindness, reliability, and emotional stability.

Are you seeing it the same way?

What you say
You rated this low. In our survey, fewer than one in five students said shared values are “pretty important.”

What the research says   
Yes. Shared core values are the game-maker, and opposing values the deal-breaker.
We are attracted to people whose attitudes and values match our own, and those relationships last longer. Core values vary from person to person, but tend to include:

  • Religious beliefs
  • Ethical issues; e.g., attitudes relating to honesty and fidelity
  • Attitudes relating to money, spending, and saving
  • Political perspective
  • Family plans; e.g., do you want kids?

Cherish your values and be alert for a potential partner who will cherish them with you. How you treat each other is also key. Among the shared values you’re looking for, prioritize kindness, respect, and thoughtful communication.

Do you like doing the same things?

What you say
Shared hobbies and activities ranked “pretty important” to more than a third of the students who took our survey. A further 51 percent said shared activities “seem to help.” You ranked this well above similar politics, worldview, values, or IQ.

What the research says
Maybe not so much. Of course, a shared interest might be how you meet. Many close relationships start with two people repeatedly running into each other—which could be on the soccer field. Alternatively, once you’re in a relationship, you might join your partner on that hike into the Rockies and learn to like it.

Although it’s important to spend time together, the relationship doesn’t necessarily have to be about your thing for Grand Theft Auto or their determination to make it to Everest base camp.

Does your voting really matter?

What you say
Is it a problem if they vote for the libertarian and you’re all about the liberal? You say no. In our survey, fewer than one in ten students thought a shared
political perspective is “pretty important” in relationships. More than one in three said it’s “hardly relevant.”

What the research says
Yes. Politics matter very much—more so than looks and personality, according to a 2011 study. Relationships that involved a shared political perspective lasted more than twice as long as those that didn’t (5.83 years vs. 2.30 years).

Regardless of whether or not we vote, political affiliation tends to represent our core values. And values matter a lot for compatibility.

Do they have to be as hot as you?

What the research says  
We value physical attractiveness a whole lot. Here’s how that works:

  • We tend to pair up with people we think are about as attractive as us. This is known as the matching hypothesis.
  • We’re tempted to think physical appearance means more than just physical appearance. In a classic study, undergrads rated more conventionally attractive people as kinder, more sensitive, more outgoing, more interesting, and more modest than their less conventionally attractive counterparts.

What if they’re good-looking—and also unkind, insensitive, and boring?
Or the other way around? Just saying.

You’re from the south side. They’re from the north side. What of it?

What you say
No. Only 16 percent of students in our survey said this was “pretty important.” Maybe we don’t like to think we’re judging people on where they’ve come from. Or that we’re being judged.

What the research says   
Yes. This might be because socioeconomics has a lot to do with our education level, political perspective, and values—which are all important for compatibility. Of course, it’s possible to derive shared values from different socioeconomic experiences, and some couples do well at this. Again, the research captures generalities, not individuals.

Be aware that it might be difficult to meet in the middle.

What if I worship Jesus and they worship Marduk?

What you say
Yes. Thirty percent of students who responded to our survey rated shared ideas about religion as “pretty important,” and almost as many said this “seems to help.”

What the research says   
Yes. Relationships are more likely to thrive when they’re founded on a shared belief system. Couples who share a religious faith have more harmonious and enduring relationships (in general) than do partners of different faiths. When only one of the two is religious, relationships tend to struggle.

In case you’re wondering, Marduk was the ancient Babylonian god of magic.
Chances are you won’t run into a Marduk worshipper.

Must we both be faithful to the idea of being faithful?

What you say
You didn’t tell us about sexual fidelity specifically, but students taking our survey ranked “ideas about sex” as the third most important shared factor in compatibility.

What the research says   
Yes. Fidelity is highly valued by men and women. It rated above looks, family commitment, and wealth and status in a study of 1,000 people age 18—24.

What the relationship expert says  
Sexual fidelity is the right choice for many couples, and sexual promiscuity generally isn’t, says Dan Savage, the media pundit. But if you’re in it for the long haul, sometimes “monogamish” is a more realistic goal. Note: Only if both partners sincerely agree. No pressure.

You can agree either that sexual fidelity is vital, or that it’s overrated. If you disagree, tread carefully.

Which compatibility factors divide men and women?

Proportion of women who say it’s importantProportion of men who say it’s importantAnd is it important?
Shared religious beliefs33%24%Yes
Shared ideas about sex54%46%Yes
Similar future goals62%46%Yes

Student Health 101 survey, October 2014. 1,600 students answered this question.

Which similarities do students overestimate and underestimate?

In our survey, students tended to overestimate the importance of…

  • Specific leisure activities
  • Personality traits

Students underestimated the importance of…

  • Political views
  • Worldview, values, and ideas
  • Education level
  • Socioeconomic background

Student Health 101 survey, October 2014. 1,600 students answered this question.

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Lucy Berrington is a health writer, editor, and communications manager. Her work has been published in numerous publications in the US and UK. She has an MS in health communication from Tufts University School of Medicine, Massachusetts, and a BA from the University of Oxford, UK.