“…Twin studies of ADHD‐like traits among children and adolescents have consistently showed strong genetic influences, with heritability estimates around 60–90% (Burt, ; Faraone et al., ), whereas both genetic and shared environmental influences seem to be important for externalizing traits, especially during childhood (Burt, ; Rhee & Waldman, ). There is also evidence that the overlap between ADHD‐like and externalizing traits, such as ODD and CD symptoms, are mainly of genetic origin (Dick, Viken, Kaprio, Pulkkinen, & Rose, ; Knopik et al., ; Nadder, Rutter, Silberg, Maes, & Eaves, ; Tuvblad, Zheng, Raine, & Baker, ); however, not all studies have reached that conclusion (Burt, Krueger, McGue, & Iacono, ).…”