This study found genetic influences for most ratings of the parent-child relationship, with evidence of gender and/or rater-specificity for some measures. The relationship between mother-child hostility with adolescent conduct problems and cigarette use was influenced by genetic and environmental effects. Evidence was found for shared environment effects on the relationship between mother-child warmth and conduct problems. It was noted that the examination of monozygotic twin differences provided further support for non-shared environmental influence on the relationship between mothers’ expressions of hostility and low warmth and adolescent adjustment. The findings in this work are discussed in relation to the interplay between genetic and environmental effects underlying links between parent-child relations and adolescent behavior problems. This study investigated genetic and environmental influences on the associations between mother-child relationship quality (warmth and hostility) and adolescent conduct problems and cigarette use. Mothers and adolescents provided separate reports of mother-to-child warmth and hostility. A combined measure of mother and adolescent reported conduct problems was used while adolescents provided reports of their cigarette use. The analyses were conducted using bivariate genetic analyses of correlated factors models and regression analyses of monozygotic twin differences. Data were derived from a group of participants which included 601 mothers and adolescent twin pairs aged 12-17 years. Tables, references