parent monitoring solely as an environmental risk, as parent monitoring itself may be influenced by both genetic and environmental factors, reflecting both genetically-influenced characteristics of the parents (39–42), though neither genetic variant examined here was correlated with parent monitoring (r=0.03, p=0.18 for rs16969968; r=−0.03, p=0.18 for rs3743078). Fifth, we found no significant difference in the associations between parent monitoring and nicotine dependence between the genders in this data by testing the interaction between gender and parent monitoring (p=0.071). The genetic risks associated with the risk genotype rs16969968 were not statistically different across gender (OR=2.15 for men; 1.82 for women). Because of the possible difference in parent monitoring across gender, we redefined our lowest quartile parent monitoring within each gender group to ensure that the comparisons are made within the same gender group. In gender-stratified analyses, we found the similar pattern of stronger gene-modifying effects of parent monitoring in females than in males. In women, OR for risk genotype = 1.49 with higher monitoring increased to 4.08 with low parent monitoring. In men, OR for risk genotype =2.03 with higher monitoring increased to 2.76 with low parent monitoring. However, there is a potential gender difference in the interaction between lowest quartile
