Twin studies of obsessive-compulsive disorder report concordance rates of about what for identical and fraternal twins?

1. Family and twin studies together suggest a moderate genetic component for obsessive-compulsive disorder. 2. The disorder is five times more frequent in first-degree relatives of affected people than in unaffected people. 3. Concordance is around 57% for identical twins and 22% for fraternal twins, and the higher figure always belongs to identical twins. 4. Reversing the two figures would imply shared genes lower the risk, which no twin design supports. 5. The pairs 67 and 16, and 50 and 38, are the twin concordance figures reported for bipolar disorder and major depressive disorder. _Source: OpenStax Psychology (1st ed., CC BY 4.0), Ch 15 "Psychological Disorders", section 15.5 Obsessive-Compulsive and Related Disorders_