Consensus estimates from over 30 twin studies indicate that the heritability of ADHD is 70–80% throughout the lifespan11,12 and that environmental risks are those not shared by siblings13. Twin studies also suggest that diagnosed ADHD represents the extreme tail of one or more heritable quantitative traits14. Additionally, family and twin studies report genetic overlap between ADHD and other conditions including antisocial personality disorder/behaviours15, cognitive impairment16, autism spectrum disorder17,18, schizophrenia19, bipolar disorder20, and major depressive disorder21.
