In 2009, Development Psychology published a study that investigated the role of sibling aggression in the development of antisocial behaviors.
The study, which was conducted by Misaki Natsuaki, Xiaojia Ge, David Reiss, and Jenae M. Neiderhiser, attempted to explain the similarity between sibling’s antisocial behaviors.
The similarity is often attributed to either shared genetics or a shared environment, but there is another possibility. “Sibling resemblance, however, could also result, at least in part, from day-to-day social interactions. Taking development of aggression, for example, Patterson and his colleagues proposed a concept of deviancy training whereby sibling aversive behavioral exchanges provide potential training grounds for the development of delinquent behavior,” as Natsuaki and his colleagues explained.
To examine the relationship between sibling aggression and the development of delinquent behaviors, Natsuaki and his colleagues analyzed data from the Nonshared Environment in Adolescent Development project (NEAD).
The Nonshared Environmental Adolescent Development project is “a longitudinal study that assessed 720 same-sex twin and sibling pairs from a nationwide sample of two-parent families, including both nondivorced and stepfamilies, with a pair of adolescent siblings no more than 4 years apart in their age.”
Using data from this project allowed the researchers to control for variables such as genetic relatedness, socio-economic status, developmental effects, and parental influences.
According to Natsuaki and his colleagues, the study found a weak but statistically significant effect between sibling aggression and the development of antisocial behaviors.
Those who had siblings that acted aggressively towards them were more likely to have problems with aggressiveness, impulsivity, school behavior, and interpersonal relationships.
“The findings from this study provide support for the assertion that patterns of irritable and aggressive exchanges provide behavioral contingencies for siblings to become fellow travelers on the path to antisocial behaviors.”
Natsuaki, M.N., Ge, X., Reiss, D. & Neiderhiser, J.M (2009) Aggressive behavior between siblings and the development of externalizing problems: Evidence from a genetically sensitive study. Developmental Psychology, Vol 45, No 4: 1009–1018.