Socially disruptive behavior during peer interactions in early childhood is detrimental to children’s social, emotional, and academic development. Few studies have investigated social behavior using genetically sensitive designs that allow examination of evocative genotype-environment correlations underlying family process and child outcome associations. Using an adoption at birth design, the present study controlled for passive genotype-environment correlation and examined the evocative effect of genetic influences on toddler inattention on mother-to-child and father-to-child hostility, and the subsequent influence of hostility on disruptive peer behavior during the preschool period. Participants were 316 linked triads of birth mothers, adoptive parents, and adopted children. Path analysis showed that birth mother underarousal predicted toddler inattention, which predicted both mother-to-child and father-to-child hostility, suggesting the presence of an evocative genotype-environment association. In addition, both mother-to-child and father-to-child hostility predicted children’s later disruptive peer behavior. Results are discussed with respect to the role of evocative and passive genotype-environment correlation in past research examining family processes and child outcomes.