Nordsletten and colleagues1 report on the first study looking atassortative mating and psychiatric disorders in a representative populationsample (of over 700 000). Compared with the general population, the odds ofhaving a partner who also suffers from a mental health problem – both withinand across disorders – were significantly elevated: cross-assortative matingwas approximately 0.15 for bipolar disorder, 0.36 for substance misuse, andover 0.40 for attention-deficit hyperactivity disorder, autism spectrumdisorder (ASD) and schizophrenia. Overall, having one of these disorders wasassociated with an approximately two- to threefold increase in the odds ofhaving a mate with the same or an alternative mental health condition.Interestingly and importantly, such cross-assortative mating was not found for a range of physicalhealth conditions, including diabetes, rheumatoid arthritis and multiplesclerosis.