A new study from the University of Colorado Boulder has delved into couple dynamics through an extensive analysis of over 130 traits, encompassing millions of couples over more than a century. Published in
Nature Human Behaviour, this research challenges established beliefs about human relationships.
The researchers used a combination of meta-analyses of previous studies and new data from the UK Biobank. They examined 22 traits across 199 studies involving millions of heterosexual couples. Additionally, they analyzed 133 traits in nearly 80,000 British heterosexual couples. Same-sex couples were not included in this research as the patterns may differ, a topic the authors are exploring separately.
The results show that people with similar traits are more likely to couple up. This study confirms that like attracts like, contradicting the adage that opposites attract.
The findings reveal that certain characteristics, such as political and religious attitudes, education level, and some IQ indices, show high correlations between partners. For example, the correlation of political values between partners reaches 0.58 on a scale where 1 signifies perfect similarity. Behaviors related to substance use, such as smoking and alcohol consumption, also display strong correlations.
Other traits, like height, weight, and certain personality traits, show weaker but still positive correlations. For example, the correlation for neuroticism is 0.11. For some traits, such as extraversion, the correlation is almost zero, meaning that extraverts are just as likely to couple with introverts as with other extraverts.
The study also shows that for a few specific traits like chronotype (preference for morning or evening), tendency to worry, and hearing difficulty, there is a slight tendency to pair with different people. However, these negative correlations are weak and require further research to be fully understood.
The most similar trait between partners is the year of birth. Even rarely studied traits, such as the number of sexual partners or breastfeeding during childhood, show some correlation. These findings suggest that unconscious mechanisms may influence our relationship choices.
The authors of the study explain that couples share traits for various reasons. Some grow up in similar environments, some are attracted to people who resemble them, and others become more alike over time. These similarities can have consequences for genetics and society. For instance, if short people tend to marry each other, likewise for tall people, it could lead to an increase in height extremes in future generations.
The researchers caution against overestimating these correlations and their use to promote a particular ideology. They hope this study will stimulate further interdisciplinary research to better understand human relationship dynamics.