quantification of some aspect of aggressive behaviour during childhood, usually assessed through the use of standardised questionnaires. Childhood aggressive behaviour is a criterion for disruptive behavior disorders such as oppositional defiant disorder (ODD) and conduct disorder (CD) [American Psychiatric Association, 2013]. Aggressive behavior is also implicated in neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD) [Hamshere et al., 2013], autism spectrum disorder (ASD) [Mandy et al., 2013], dysregulated behavior [Pope and Bierman, 1999], substance use disorders [White et al., 2013], antisocial personality disorder [Schaeffer et al., 2003], and schizophrenia [Volavka, 2013] later in life.