Date of Award

Spring 1-1-2017

Document Type


Degree Name

Doctor of Philosophy (PhD)


Psychology & Neuroscience

First Advisor

Michael C. Stallings

Second Advisor

John K. Hewitt

Third Advisor

Matthew C. Keller

Fourth Advisor

Stefanie Mollborn

Fifth Advisor

Soo H. Rhee


Previous studies suggest that risky sexual behaviors (RSB) are highly correlated with impulsive behaviors such as substance use disorders, antisocial behavior, and novelty seeking. The comorbidity of these latter behaviors is well described by an underlying heritable factor termed behavioral disinhibition (BD). To better understand the nature of this correlation, this dissertation explores the extent to which this overlap is genetic or environmental in nature. Multivariate biometrical models with twin and adoptive samples are used in Chapters II and III to assess developmental trends in substance use behaviors and to explore the shared etiology between sex under the influence of drugs and alcohol and number of lifetime sexual partners. Chapter II included an in depth review of issues regarding measuring and defining RSB, with the goals of improving an instrument for measuring sexual behavior, improving the interpretation of several RSB variables, and selecting an optimal phenotype for use with genome wide methods. Finally, Chapter V used several genome-wide approaches to explore the genetic architecture of number of lifetime sexual partners and to test the genetic overlap with measures BD related diseases and traits (e.g. smoking, psychiatric, personality), and other fitness phenotypes.