Familial Clustering of Trends in Aggression

Abstract Objectives Examine trends in aggressive behavior from 1991 to 2015, investigate whether these apply equally all individuals, and explore the extent which differences over time cluster within families. Methods Our study included 69,465 measures 40,400 15,437 Dutch Aggression was measured between 1 4 times by self-report. We fitted a mixed effects model, modeling effect of time, age, gender on aggression, considering three levels nesting data, i.e. repeated measures, To if individual aggression families, variance age partitioned into within- family components. Results found steady decline as well life course. Across women had slightly higher than men. There clear evidence for clustering within, variation both overall effects. Conclusions confirm earlier findings past decades. Not individuals follow downward trend same extent. Trends demonstrating that factors are not only important explain levels, but also understanding trends.