Obsessive-compulsive disorder, tics and anxiety in 6-year-old twins
Background. Previous reports of genetic influences on obsessive–compulsive disorder (OCD) symptoms have suggested moderate heritability. Family history studies of co-morbidity have found familial aggregation with tics, especially for early-onset OCD, and familial aggregation with anxiety disorders. Method. Heritability of OCD and familial aggregation of OCD, tics and anxiety disorders were investi