Sibling influences on adolescent drug use: older brothers on younger brothers.

This study was designed to examine sibling influences on adolescent drug use. The sample was composed of 278 white, predominantly middle-class male college students and their oldest brothers. Self-administered questionnaires were taken separately by the students and their brothers. The findings indicated that the oldest brother's personality and the sibling relationship had an influence on the younger brother's drug use. Three hypothesized mechanisms that supported the findings, the Personality Influence Mechanism, the Genetic Temperament Connection, and the Environmental Reactive Mechanism were discussed.