The remaining six domains showed a more restricted pattern (present for ADHD and/or CD, but not yet studied or not reported for IED): maternal smoking during pregnancy, maternal alcohol use during pregnancy, low birth weight/other perinatal risks, parental psychopathology/maternal mental health, MAOA/COMT genetic variants and parenting stress/school‐related disadvantage that has not been tested for IED. Here, COMT is linked to attention deficit-hyperactivity disorder.