Home environment quality is a well-known predictor of school readiness (SR), although the underlying processes are little known. This study tested two hypotheses: (a) child language mediates the association between home characteristics (socioeconomic status and exposure to reading) and SR, and (b) genetic factors partly explain the association…

This study investigated associations between maternal prenatal smoking and physical aggression (PA), hyperactivity-impulsivity (HI) and co-occurring PA and HI between ages 17 and 42 months in a population sample of children born in Quebec (Canada) in 1997/1998 (N=1745). Trajectory model estimation showed three distinct developmental patterns for…

Two cohorts of same-sex twin pairs were assessed on grammar and vocabulary. Findings indicated that vocabulary and grammar correlated strongly at 2 and 3 years in both cohorts, with a consistently high genetic correlation between vocabulary and grammar at both ages. Findings suggest that the same genetic influences operate for vocabulary and…

The goal of this study was to examine the links between difficult temperament (i.e., negative emotionality) and harsh parental discipline during toddlerhood, and reactive and proactive aggression in kindergarten. These links were assessed on a longitudinal population-based study of 1516 boys and girls followed longitudinally from the age of 17…