Tobacco use remains the leading preventable cause of morbidity and mortality in both the United States and worldwide. Twin and family studies have demonstrated that both genetic and environmental factors are important contributors to tobacco use behaviors. Understanding how genes, the environment, and their interactions is critical to the development of public health interventions that focus on the reduction of tobacco related morbidity and mortality. However, few studies have examined the transition from adolescent to young adulthood – the time when many individuals are experimenting with and developing patterns of tobacco use. This dissertation thesis seeks to provide a comprehensive set of studies looking at risk for tobacco use behaviors and nicotine dependence using samples of young adults. The first aim is to examine the joint contributions of genetic liability and environmental contexts on tobacco use in adolescence and young adulthood using classical twin study methodologies. The second goal is to identify genetic variants and quantifying genetic risk for tobacco use in young adulthood and examining their interaction with environmental context across development. Accordingly, the thesis is divided up into the following sections: i) reviews of existing literature on genes, environment, and tobacco use; ii) twin studies of genetic and environmental influences on tobacco use behavior phenotypes; iii) prevalence, correlates, and predictors of tobacco use behaviors; iv) genetic analyses of tobacco use behaviors; v) a commentary on the emergence of alternative nicotine delivery systems and its public health impacts; and vi) plans for an internet-based educational intervention seeking to reduce tobacco use (and nicotine dependence) by providing students attending university with information on genetic and environmental risk factors for nicotine dependence.

Objective. To examine alternative tobacco product (ATP) use and associated factors among middle school students in Appalachian Tennessee. Method. Data (2015– 2016; N=573) from school-based tobacco surveys in 11 middle schools in Appalachian Tennessee were analyzed. Multiple logistic regression model described factors associated with ATP use. Results. More than one-tenth (13.2%) of participants have ever used ATPs. Approximately 9%, 7%, 6%, and 2% of participants have ever used e-cigarettes, cigarettes, smokeless tobacco, and little cigars or cigarillos, respectively. The following were significantly associated with ever use of ATPs: believing tobacco users have more friends, owning tobacco-branded item(s), living with a tobacco user, having ever smoked cigarettes, and living in homes where smoking is allowed. Conclusion. More than one in 10 of participants have ever used at least one ATP, and association with desirable objects and situations may promote ATP use. Interventions should seek to reduce these positive images and make all tobacco products unappealing.