This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin Study completed inventories describing delinquency and substance use at ages 13, 14, and 15. A 3-wave longitudinal actor-partner…

This study investigated the normative use and developmental course of physical aggression (PA), defined as use of physical force such as hitting, biting, and kicking, from 8 to 26 months and predictors thereof. We used data from the Behavior Outlook Norwegian Developmental Study, comprising 1,159 children (559 girls and 600 boys). Both mothers and…

The National Center on Addiction and Substance Abuses surveys have consistently found that the family is fundamental to keeping children away from tobacco, alcohol and illegal drugs. This 2002 survey keeps the focus on family and seeks to assess the impact of siblings on the likelihood of teen substance abuse. This year 1,000 teens ages 12 to 17…