A new study published in Personality and Individual Differences highlights that romantic partners often exhibit similar levels of Machiavellianism, narcissism, and psychopathy—collectively known as the “dark triad” of personality traits. Researchers found evidence that these similarities are present early in relationships, suggesting that people may actively seek partners with similar dark traits, rather than becoming more alike over time.
The study was motivated by a desire to better understand assortative mating, a concept that describes the tendency for people to form romantic relationships with partners who are similar to them in important traits. While previous research has extensively documented assortative mating for demographic factors like age, education, and shared interests, less attention has been given to assortative mating for personality traits that are socially undesirable, particularly the “dark triad” traits.
The dark triad refers to three specific personality characteristics: Machiavellianism, narcissism, and psychopathy. Each of these traits is considered socially aversive and can have a significant impact on how people behave in relationships.
Machiavellianism is characterized by manipulativeness, strategic behavior, and a cynical view of the world. Individuals high in Machiavellianism tend to prioritize personal gain, often at the expense of others. They may engage in deceptive behavior, use others to achieve their goals, and show little regard for ethical or moral considerations.
Narcissism, in this context, refers to subclinical narcissism, which includes traits such as grandiosity, entitlement, and a strong need for admiration. People high in narcissism often see themselves as superior to others and expect special treatment. While they can be charming and self-confident, they may also lack empathy and be preoccupied with their own success and image.
Psychopathy, also in its subclinical form, is associated with impulsivity, a lack of empathy, and a disregard for social norms. Individuals with high levels of psychopathy may engage in reckless or antisocial behavior, have difficulty forming deep emotional connections, and be more prone to thrill-seeking or harmful actions without considering the consequences for others.
These dark traits are often seen as problematic in interpersonal relationships. People with high levels of these traits may struggle with long-term commitment, empathy, and cooperation, which are generally important for successful romantic relationships. They also tend to be manipulative and are more likely to engage in gaslighting. However, the researchers in this study wanted to explore whether individuals with these traits tend to seek out partners who share similar tendencies.
To investigate this, the researchers conducted three separate studies. The first study, based in the UK, involved 104 heterosexual couples who had been together for varying lengths of time, from one month to nearly 60 years. Participants completed the Short Dark Triad questionnaire. Additionally, the couples reported various demographic details, such as their ages, relationship length, and educational backgrounds. The second study, conducted in Fiji, included 99 heterosexual couples and used a similar procedure, though with some additional measures related to dark personality traits. Finally, the third part of the research was a meta-analysis of previous studies examining partner similarity for dark triad traits across different cultures and populations.
The results of the UK and Fijian studies revealed that romantic partners exhibited moderate similarities for Machiavellianism, narcissism, and psychopathy. This partner resemblance was stronger than would be expected by chance, suggesting that people with higher levels of dark triad traits are not randomly pairing up with just anyone—they are likely choosing partners who share these tendencies. The researchers also compared couples to randomly paired individuals and found that real couples were significantly more alike in their dark triad traits than these artificial pairings.
One key insight from the study was that this partner similarity seems to be explained by initial and active assortment, rather than convergence or social homogamy. Initial assortment means that people enter into relationships with partners who are already similar to them, while active assortment implies that individuals may be consciously seeking out partners with similar characteristics.
In contrast, convergence would suggest that partners become more alike over time through shared experiences, and social homogamy would indicate that people select partners from the same social or cultural groups, leading to similarities based on shared environments. However, the data did not support these latter explanations, as couples’ dark triad traits were not more similar the longer they had been together, nor did factors like age, education, or religious beliefs correlate with the similarity of their dark triad traits.
The meta-analysis in the third part of the study further confirmed that assortative mating for dark triad traits is a robust phenomenon. Across multiple studies and different cultures, the researchers found consistent evidence of positive assortment for these traits. Interestingly, Machiavellianism showed the strongest assortative effects, potentially because this trait is closely tied to individual values and ethical beliefs, making it a particularly salient factor in partner selection.
The results are in line with a previous study, which found that individuals with dark triad traits tend to be more satisfied in their romantic relationships when their partner possesses similar traits. The research, which involved 205 couples, found that similarities in these traits, particularly in psychopathy and narcissism, were linked to higher relationship satisfaction.
While the new findings shed important light on how dark triad traits influence partner choice, the study also has limitations. First, it relied on self-reported data, which could be subject to biases, particularly since people with high levels of these traits might be less honest or self-aware. Additionally, the study was cross-sectional, meaning that it could not definitively rule out the possibility of convergence over longer time periods, or the potential for couples with greater differences in dark triad traits to break up earlier in their relationships.
Future research could address these limitations by using longitudinal designs to track changes in partner similarity over time and by including more diverse samples in terms of education, socioeconomic status, and culture. It would also be beneficial to examine how these dark triad traits interact with other aspects of personality and relationship dynamics, such as conflict resolution or satisfaction, to better understand their broader impact on relationships.
The study, “Assortative mating and the dark triad: Evidence from the UK, Fiji, and meta-analytic review,” was authored by Gareth Richards, Hannah Proctor, Eva Lee, Ofa Swann, Emily Jackson, John Galvin, Robin I.M. Dunbar, Simon Baron-Cohen, and Shanhong Luo.
