ABSTRACT
Aggressive behaviors, as well as biological and social risk factors for aggression, are highly stable over time. In a 22-year longitudinal study, the individuals who were most aggressive at the age of 8 years continued to be the most aggressive at the age of 30; stability of aggression was .50 for boys and .35 for girls over this 22-year period (Huesmann et al., 1984). However, there is some evidence that a number of environmental factors can affect the stability of aggression. For example, aggression is more stable from childhood to adulthood in the United States than in Finland (Kokko et al., 2014), perhaps in part because of macro-environmental features of Finland that make it easier for individuals to break out of aggressive trajectories (e.g., free access to higher education in Finland but not in the United States). Thus, it is important to understand factors that promote stability versus change in the development of aggression.
