Personality and relationships, how much do traits really matter

Personality matters in a relationship, but not in the way people usually think. Studies of tens of thousands of couples show that what counts most is each person's own traits, yours and your partner's. Similarity between the two, what dating sites call compatibility, adds almost nothing.

Your own traits count more than your partner's

The largest study of this question analyzed married couples from three national samples, in Australia, the United Kingdom and Germany, each with thousands of couples (Dyrenforth and colleagues, 2010). A person's own traits explained about 6% of the differences in their relationship satisfaction. The partner's traits added 1% to 3%, mostly through Agreeableness, Conscientiousness and emotional stability.

A meta-analysis of 19 samples and 3,848 people points the same way: people whose partners are lower in Neuroticism and higher in Agreeableness, Conscientiousness and Extraversion tend to be more satisfied, with no difference between men and women or between married and unmarried couples (Malouff and colleagues, 2010). A later review confirms Neuroticism, Agreeableness and Conscientiousness as the recurring traits (Weidmann, Ledermann and Grob, 2016).

Six percentage points may sound small, and it is: most of relationship satisfaction depends on other things, from the history of the relationship to life circumstances. But the effect shows up in every country studied, and it lasts. In a representative sample of 8,206 people followed over years, traits also predicted breakups, largely through satisfaction (Solomon and Jackson, 2014).

Being alike barely helps

Here the evidence is clear. In the three-country study, once each partner's own traits were accounted for, similarity always explained less than 0.5% of satisfaction (Dyrenforth and colleagues, 2010). A finer analysis of 237 couples, which also looked at non-linear combinations, found a negligible role for similarity, with only two isolated effects over time (Weidmann and colleagues, 2017). And in 1,294 couples, similarity was not robustly linked to satisfaction even at the level of facets (Weidmann and colleagues, 2023).

Partners are not very alike anyway

A large synthesis measured how similar partners are on 22 characteristics. For the Big Five, correlations ranged from .08 for Extraversion to .21 for Openness (Horwitz and colleagues, 2023). Those are low: partners are far more alike in political values (.58), religiosity (.56) and education (.55). Extraversion, Neuroticism and Agreeableness were among the characteristics on which couples resemble each other least.

The idea that opposites attract finds no support either: the correlations are low but positive. People do not seek someone different; on personality, their choice is just close to random compared with other characteristics.

What to make of it

If you are looking to personality for the formula of the perfect couple, the data do not offer one. What they offer is more useful: knowing your traits, and perhaps your partner's, helps explain where recurring friction comes from, such as who worries more about the same things or who needs more order at home. It does not predict whether a relationship will work. You can see your five traits with the test below, which takes about 10 minutes.