Shared genetic influences on adolescent body mass index and brain structure: A voxel-based morphometry study in twins.

•Gray and white matter volume and density are related to adolescent BMIz.•Adolescent BMIz and brain structure are both heritable.•BMIz and certain brain structures share ∼1/3 of their genes.•∼95% of the phenotypic correlation is due to shared genetic influences.•Frontotemporal, insular, cingular, cerebellar, thalamic, brainstem areas implicated.