Are there Complex Assortative Mating Patterns for Humans? Analysis of 340 Spanish Couples

Assortative mating for both physical and psychological traits is well-established in many animal species, including humans. Most studies, however, only compute linear measures of mate similarity, typically Pearson correlations. However, it is possible that trait similarity, or dissimilarity, has complex patterns missed by the correlation metric. We investigated a dataset of 340 Spanish couples for evidence of relationships across 7 traits: age, educational attainment, intelligence, and the scales of the Eysenck Personality Questionnaire: Extroversion, Psychoticism, Neuroticism, and the Lie scale. We replicated well known linear assortative mating for age, intelligence and education. Like most studies, we find weak to no assortative mating for the personality traits. Analysis of nonlinear patterns using regression splines failed to reveal anything beyond the linear relations. Finally, we examined cross-trait variation for couples but we found little of note. Overall, it does not appear that there are complex patterns for traits in human couples.