The document discusses various factors that influence aggression in sport, including social learning theory, personality traits, gender differences, arousal, hormones, morality, and collective aggression among fan groups. Social learning theory posits that people learn aggression through observation and modeling. Personality traits like high competitiveness and testosterone levels may also impact aggressive tendencies. Gender socialization teaches men that aggression is more acceptable. The group dynamics of fan cultures can encourage collective aggression toward opposing fans.