Twins in a child psychiatry clinic.

The authors found that 22 of the 2,015 referrals to a children's psychiatric clinic during a six-year period were twins--half the number that would be expected on the basis of the national incidence of twins. Evidence of minimal brain dysfunction was found in a higher percentage of the twins than in a matched nontwin group. The authors suggest that factors often inherent in twins (e.g., prematurity and birth difficulties) may be related to this finding.