Transmission of symptoms of anxiety and depression in nuclear families.

Anxiety and depression symptom scores from the SCL-90 questionnaire were observed in a large sample of nuclear families, and the effects of genes or family environment were estimated. Assuming no environmental transmission from parents to offspring, heritability was estimated at 0.43 for both anxiety and depression scores, and common sibling environment or reciprocal sibling influence explained 19% of the variances for both scores. Most of the (genetic or environmental) family effect seemed to be common for the two scores. There was no evidence of common determinants in the family for the symptom scores and alcohol consumption, not even of any substantial relationship within persons between symptoms and consumption. The spouse correlations were 0.25 for anxiety and 0.38 for depression. Similar values for the correlations between anxiety in one person and depression in his/her spouse implies a mate selection based on a single latent variable to which the two observed traits contribute.