The comparison between pediatric and adult studies indicated that OCD was significantly more familial in children/adolescents than in adults. First-degree relatives of the child and adolescent OCD probands had a 16 times higher risk of definite OCD compared to the control FDRs (OR = 16.44, 95% CI 4.57–59.17, p < 0.00001). The FDRs of adult OCD probands had an approximately 6 times higher risk of definite OCD compared to the control FDRs (OR = 6.02, 95% CI 3.16–11.46, p < 0.00001) (Fig. 3).
