“…Gender was a moderator of aggressive behaviour. Males exhibited more physical and verbal violence (Anderson & Bushman, ; Archer, ; Calvete & Orue, ; Cohn, ; Hyde, ; Knight, Fabes, & Higgins, ; McGue, Bacon, & Lykken, ; Pahlavan, Mouchiroud, & Nemlaghi‐Manis, ; Schober, Bjarkqvist, & Somppi, ), while women reported higher levels of indirect or relational violence (Anderson & Bushman, ; Björkqvist, Osterman, & Kaukiainen, ; Crick & Grotpeter, ; Hess & Hagen, ; Pahlavan et al., ; Schober et al., ). These gender differences in the display of aggressive behaviour begin in preschool (Maccoby & Jacklin, ), and increase from 18 to 30 years, coinciding with the peak of reproductive activity consistent with the Sexual Selection Theory's emphasis on greater inter‐male competition during this age range (Archer, ).…”