This statement is supported by the fact that on a behavioral level DRD4-7r has been related to aggression in children (Schmidt et al. 2002), to conduct problems and oppositional behavior in individuals with Attention Deficit Hyperactivity Disorder (ADHD; Holmes et al. 2002; Kirley et al. 2004), and to diminished levels of prosocial behavior (Anacker et al. 2013; DiLalla et al. 2009; Jiang et al. 2013). This evidence concerns the gene DRD4 and attention deficit-hyperactivity disorder.