Despite important sex differences, our continuity analyses underline the critical observation that continuity in aggressive behavior is a population-level phenomenon that is not driven principally by highly aggressive individuals remaining so over their life course. This lends weight to the common assertion that aggressiveness is in essence a relatively stable behavioral trait that can be measured reliably as an individual-difference variable [Huesmann and Eron, 1989]. Of course, individuals “move out” of relatively high or low positions in the population, and the exploration of factors accounting for this instability is a critically important task for future research. Given the moderate genetic heritability of aggression [Miles and Carey, 1997] and tendency for cross-generational behavioral modeling and social transmission of aggressiveness [Dubow et al., 2003], the factors accounting for changes in individuals’ propensities to behave aggressively are probably environmental and most likely extra-familial as well.
