Regional variation and urban-rural differences in partner similarity: a nationwide cohort study
Although romantic partners tend to resemble each other on many characteristics, the geographical processes underlying partner similarities remain poorly understood. Using Finnish nationwide registry data from cohabiting or married partners (N = 1,500,204 couples; partnerships were formed between 1990-2023), we examined regional differences in partner similarity in mental disorders, educational attainment, and adolescent school performance. We also analysed geographical variation in partner similarity within three major cities. Accounting for local demographic composition of potential partners attenuated the partner similarity from r=0.43 to r=0.34 for highest obtained educational attainment, but increased partner similarity in any mental disorders from r=.40 to r=.42. In urban municipalities partners were more similar in educational attainment, but less in mental disorders, compared to more rural regions. We found no clear within-city variation in partner similarity. These findings highlight the role regional demographic composition plays in partnership formation and suggest different partnering dynamics depending on societal organization.