Examining Genetic and Environmental Effects on Reactive Versus Proactive Aggression”

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Examining Genetic and Environmental Effects on Reactive Versus Proactive Aggression”

Introduction Prior to this study, no other research had studied the genetic and environmental influences on reactive and proactive aggression. The purpose of this study was to explain how much genes and (shared and non-shared) environmental factors each contribute to aggression, specifically proactive and reactive. Once a positive correlation between the two types of aggression was determined, a “sub-purpose” was to find out if any correlation was due to another common factor, such as physical aggression. And, which factors are unique to proactive aggression and which are unique to reactive aggression. The article defines proactive aggression, or …show more content…

However, there should also be non-overlapping/non-correlated factors contributing as well, as reactive and proactive aggression have different predictors, associations and ‘temperamental and physiological correlates’. With these new developments, the researchers carried out a separate test, recalculating a correlation factoring in the possible overlap of physical aggression.
Sample. The participants of this study were 6-year-olds (N= 72.7 months) selected from another current study, the Quebec Newborn Twin longitudinal Study. They initially enrolled 648 pairs of twins but the final sample size was 172 twins (55 monozygotic girls, 48 monozygotic boys, 33 dizygotic girls, and 36 dizygotic boys) after excluding data from different-sex twins and twins who were in the same class (which might indicate exaggerated similarities between the twins if rated by the same teacher). The children’s reactive and proactive aggression levels were measured using Dodge and Coie’s (1987) assessment, using informant reporting. The informant was the childrens’ kindergarten teacher during the spring (enough time for the teacher to get to know the child) in his/her preferred language (either English or French; translated twice and approved by binglingual judges). The children’s physical aggression was measured using the Preschool Behavior Questionnaire developed by Behar & Stringfield (1974),

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