Then, using fMRI and EEG we found that RH bias in ADHD was mainly evident during sub-executive operations (15), and that it exhibited: a unique developmental course among families heavily loaded for non-persistent ADHD (16), stronger expression with greater ADHD family loading (16), and stronger expression among carriers of the DRD4–7 repeat allele and other ADHD risk factors (unpublished). This evidence concerns the gene DRD4 and attention deficit-hyperactivity disorder.