This article was originally published by U of T News. Republished here with permission

In the classic romantic comedy Bridget Jones’s Diary, Jones begins the new year with a resolution: “Will find nice sensible boyfriend and not continue to form romantic attachments to alcoholics, workaholics, peeping-toms or megalomaniacs.”

But she immediately flirts and falls into a relationship with her philandering boss – the farthest thing possible from a “sensible boyfriend.”

“It's common that when a relationship ends or after a series of relationships that people attribute the breakup to their ex-partners’ personalities and decide they need to date a different type of person,” says Yoobin Park, a PhD student in the University of Toronto’s department of psychology in the Faculty of Arts & Science. “However, our research suggests there’s a tendency to continue to date a similar personality.

“If you find you’re having the same issues, relationship after relationship, you may want to think about how gravitating toward the same personality traits in a partner is contributing to the consistency in your problems.”

Park’s observation emerges not from a dating advice column or podcast about romantic comedies, but in a research paper published in the Proceedings of the National Academy of Sciences. The paper is co-authored by Park’s supervisor, Geoff MacDonald, a professor in the psychology department.

For the study, Park and MacDonald compared the personalities of current and ex-partners of 332 people using data gathered by the partners themselves. Their main finding was the existence of a significant consistency in the personalities of an individual’s romantic partners.

“Our study suggests that people, to some degree, have a type when it comes to the personality of who they date,” says MacDonald.

“This effect is more than just a tendency to consistently date someone similar to yourself.”

The data came from a nine-year study conducted in Germany that measured responses to 21 statements such as:

• I am usually modest and reserved

• I get enthusiastic easily and can motivate others easily

• I tend to be the strong and silent type

• I am extroverted

• I am relaxed and don’t let myself be worried by stress

• I am intellectual and like to contemplate things

• I appreciate artistic and aesthetic impressions

Respondents were asked to rate their agreement or disagreement with the statements on a five-point scale.

Analysis of the data accounted for biases that had not been accounted for in other studies. For example, other studies used an individual’s description of their partners – not the partner’s descriptions of themselves.

The analysis also minimized the possibility that any similarity was due to choosing partners who have personalities similar to our own.

Based on the findings, Park suggests that dating websites and apps could do a better job of matching potential partners. Typically, such services pair individuals using criteria like education, drinking and smoking habits, income, hobbies and activities.

“These websites and apps might want to incorporate information about ex-partners in their algorithms in the same way that music apps use past listening preferences to predict what else a listener might enjoy,” says Park.

The research also points to ways of keeping relationships healthy and happy.

“In every relationship people learn strategies for working with their partner's personality,” says Park. “If your new partner's personality resembles your ex-partner's personality, transferring the skills you learned might be an effective way to start a new relationship on a good footing.”