When it comes to traits we look for in an ideal partner, chances are impulsivity, neuroticism, and obsessive compulsiveness don’t make the list. However, people with these pathological personality traits do seem to do better with romantic relationships. According to a recent study published in the journal Evolution and Human Behavior, they end up having more partners and children over their lifetimes. So, what makes people with these personalities so desirable when their behaviors are typically frowned upon?

Fernando Gutiérrez, from the Hospital Clinic of Barcelona, and his colleagues analyzed data involving nearly 1,000 heterosexual men and women with a wide range of pathological personality traits, some of which could be diagnosed as disorders. Referred by their physicians or other medical professionals, the participants reported lifetime number of partners, job level, income, and other sociodemographic factors in surveys and interviews with the researchers.

The findings revealed people with pathological personality types, such as neuroticism and impulsivity, had more partners and even more children than average. However, results differed between men and women. Obsessive compulsive men were more successful in finding long-term partners than women. Meanwhile, women on the high end of the neurotic spectrum were 34 percent more likely to have long-term partners and 73 percent more likely to have a higher-than-average number of children — this was despite possessing a trait affiliated with instability, anxiousness, and insecurity.

The study suggests these personality traits may hold an evolutionary advantage. Participants with obsessive-compulsive personalities, for example, may have had more appeal and relationship success because they made nearly twice as much money as people who didn't have these traits. “From a Darwinian viewpoint, money means survival, safeness, and resources for the children.” People with obsessive-compulsive personalities are “also serious, reliable, and cautious,” Gutiérrez told Scientific American.

People with other personality traits, like impulsiveness and risk-taking, have been shown to attract people because they’re considered captivating. From an evolutionary basis, this rash and rule-breaking behavior could function as a fitness indicator, pointing to how healthy the person is. This is “a signal that the subject has such good genetic quality and condition as to live dangerously without suffering harm,” Gutiérrez said.

Previous research has delved into the sex appeal behind these so-called “dark” personality traits. A 2012 study, for example, found people who scored high in traits like narcissism and psychopathy were considered more physically attractive because of their ability to create positive first impressions. A high score on the “dark triad” of personality traits — narcissism, Machiavellianism, and psychopathy — was correlated with a better ability to make themselves physically appealing. Narcissists tend to be better at building an attractive identity and an alluring image while also displaying self-confidence, all of which which people are drawn to.

It seems that despite these dark personality traits being eccentric and troublesome, we’re drawn to them for these exact reasons. These personality traits may actually help us survive in the world. So, to be an “odd ball” doesn't mean the person is imperfect. Perhaps there is some truth to being crazy in love.

Sources: Vall G, Gutiérrez F, Peri JM et al. Seven Dimensions Of Personality Pathology Are Under Sexual Selection In Modern Spain. Evolution & Human Behavior. 2015.

Holtzman NS and Strube MJ. People With Dark Personalities Tend to Create a Physically Attractive Veneer. Social Psychological & Personality Science. 2012.