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 ...

This study examined whether social contagion of anxiety symptoms is present between siblings during early adolescence and whether this process is moderated by sex, relationship quality, and zygosity. Based on 634 monozygotic ...