Symptom patterns and causes of somatization in men: II. Genetic and environmental independence from somatization in...

The genetic and environmental antecedents of clinically distinct disorders leading to somatization were compared in 807 Swedish men and 859 Swedish women adopted at an early age by non-relatives. Asthenic somatization, the predominant form in men, was a neurotic disorder associated with a lower incidence of criminality in the somatizers' biological parents than in the biological parents of non-somatizers of either sex. In contrast, most female somatizers and a minority of men with diversiform somatization had disorders that were associated with a higher incidence of criminality in their biological parents than in other biological parents. Likewise, female somatizers, but not male somatizers, had an excess of alcoholic biological fathers when compared to other adoptees. In addition, different postnatal environmental background factors contributed to the risk for somatization in each sex. These findings support the distinctions among the different types of somatizers and show that the usual causes of somatization are fundamentally different in men and women. This illustrates the utility of the adoption paradigm in resolving genetic and environmental contributions to the familial aggregation of developmentally complex phenotypes.