Examining Genetic and Environmental Effects on Reactive Versus Proactive Aggression”

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Examining Genetic and Environmental Effects on Reactive Versus Proactive Aggression”


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 instrumental aggression as “offensive, and cold-blooded, requires neither provocation nor anger” and reactive aggression as “affective, defensive, and hot-blooded, involving angry outbursts in response to actual or perceived provocations or threats” (Brendgen et al., 2006, page 1299).

At the time of this study the specific genes related to aggression expression were not known, so it would have been impractical for the genotype to be assayed. Evidence for genetic influence on aggression is seen in temperament, which is extremely heritable, and associated with reactive and proactive aggression. Additional evidence lies in skin conductance induced by stress; both reactive and proactive kids exhibit higher levels of skin conductance, a physiological response. Thus, in lieu of a genetic examination, the researchers utilized the benefits of monozygotic twins’ identical genome to assess the genetic, shared environmental, and non-shared environmental influence.

The ‘subpurpose’ of this study was br...

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....13, 0.22, and 0.16, respectively). This implies a significant genetic influence on aggression (reactive, proactive and physical).

Next they used structural equation modeling and a univariate model with ‘chi-square statistics, the Akaike information criterion, the Bayesian information criterion, the comparative fit index, and the root-mean square error of approximation’ to obtain the best-fitting and most probable model, AE. From this we gained aggression variance: for reactive aggression, 39% was found to be due to genetics and 61% was due to nonshared environmental factors

Reference List

Brendgen, M., Vitaro, F., Boivin, M., Dionne, G., & Pérusse, D. (2006). Examining genetic and environmental effects on reactive versus proactive aggression. Developmental Psychology, 42(6), 1299-1312. doi:http://dx.doi.org/10.1037/0012-1649.42.6.1299

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