Aggression in adolescents is influenced by siblings Children who have older brothers are more aggressive over period, on average, than those who have older sisters. Older siblings with young sisters become less intense. Children with older sisters who are very aggressive become more aggressive and old siblings with youthful brothers showed fairly stable levels of aggression over time http://www.sildenafil-online.org/contact-us . In sum, the presence of both old and youthful siblings influences the advancement of intense behavior in adolescence. Having a brother or a highly intense sibling of either gender can result in greater boosts in aggression as time passes.