Overview
- Researchers analyzed registry data on roughly 14.8–15 million people in Taiwan, Denmark and Sweden across birth cohorts from the 1930s to the 1990s.
- Across nine conditions, people with psychiatric disorders were far more likely to marry partners with the same diagnosis than to have spouses without a disorder.
- Couples were more likely to share the exact disorder than to have different psychiatric conditions, reinforcing a pattern of diagnosis-specific pairing.
- The tendency appeared in multiple cultures and generations and persisted through major system changes, such as Taiwan’s adoption of universal healthcare in 1995.
- Differences emerged for OCD, bipolar disorder and anorexia nervosa, and partner similarity rose modestly by decade, particularly for substance-use disorders, while causes remain unproven with proposed mechanisms including assortative attraction, convergence and stigma-limited partner pools.