title: Aggression can be contagious: Longitudinal associations between proactive aggression and reactive aggression among young twins.
abstract: The present study examined sibling influence over reactive and proactive aggression in a sample of 452 same-sex twins (113 male dyads, 113 female dyads). Between and within siblings influence processes were examined as a function of relative levels of parental coercion and hostility to test the hypothesis that aggression contagion between twins occurs only among dyads who experience parental coerciveness. Teacher reports of reactive and proactive aggression were collected for each twin in kindergarten (M = 6.04 years; SD = 0.27) and in first grade (M = 7.08 years; SD = 0.27). Families were divided into relatively low, average, and relatively high parental coercion-hostility groups on the basis of maternal reports collected when the children were 5 years old. In families with relatively high levels of parental coercion-hostility, there was evidence of between-sibling influence, such that one twin's reactive aggression at age 6 predicted increases in the other twin's reactive aggression from ages 6 to 7, and one twin's proactive aggression at age 6 predicted increases in the other twin's proactive aggression from ages 6 to 7. There was also evidence of within-sibling influence such that a child's level of reactive aggression at age 6 predicted increases in the same child's proactive aggression at age 7, regardless of parental coercion-hostility. The findings provide new information about the etiology of reactive and proactive aggression and individual differences in their developmental interplay.
authors: Florida Atlantic University, Boca Raton, Florida.
authors: Daniel J
authors: DJ
authors: Dickson
authors: Florida Atlantic University, Boca Raton, Florida.
authors: Ashley D
authors: AD
authors: Richmond
authors: University of Québec, Montréal, Canada.
authors: Mara
authors: M
authors: Brendgen
authors: University of Montréal, Montréal, Canada.
authors: Frank
authors: F
authors: Vitaro
authors: Florida Atlantic University, Boca Raton, Florida.
authors: Brett
authors: B
authors: Laursen
authors: Laval University, Québec City, Canada.
authors: Ginette
authors: G
authors: Dionne
authors: Laval University, Québec City, Canada.|Tomsk State University, Tomsk, Russia.
authors: Michel
authors: M
authors: Boivin
mesh_terms: D000328:Adult; D000374:Aggression / Q000523:psychology*; D002648:Child; D005260:Female; D006791:Hostility; D006801:Humans; D007100:Imitative Behavior; D008137:Longitudinal Studies; D008297:Male; D010287:Parent-Child Relations; D014429:Twins, Dizygotic / Q000523:psychology; D014430:Twins, Monozygotic / Q000523:psychology
keywords: actor-partner interdependence model; proactive aggression; reactive aggression; sibling influence; twins