Genetic and environmental influences on the co-occurrence of early academic achievement and externalizing behavior

• A relationship between academic achievement and externalizing behaviors is observed in children.
• Academic achievement and externalizing behaviors may be due to common influences.
• The same genetic factors modestly contribute to covariation in both phenotypes.
• The same shared environmental factors make moderate to strong contributions to the covariation.
• Minimal nonshared environmental influences contribute to the covariation.

PurposeSeveral studies have observed a relationship between academic achievement and externalizing behaviors, both of which are predictors of delinquency and criminal behavior in adulthood. There is, however, no consensus on an explanation for their co-occurrence. One perspective is that both emerge as a result of a common underlying factor. This study investigates the degree to which the same genetic and environmental factors account for the co-occurrence of these two outcomes.MethodsThe sample consists of twins (N = 360) from the Early Childhood Longitudinal Survey-Kindergarten Class of 1998-1999. Bivariate genetic analyses were conducted to assess the genetic and environmental influence on the relationship between academic achievement and externalizing behaviors during kindergarten.ResultsThe covariation was due primarily to common shared environmental factors (55-87%), followed by common genetic (8-44%) and nonshared environmental factors (1-13%).ConclusionsBoth early academic achievement and externalizing behaviors are partially influenced by the same genetic and environmental factors. The large proportion of covariance attributed to shared environmental influences suggests that identifying and targeting shared environmental factors in prevention and intervention strategies may improve both behavior and academic achievement.