Is sexual orientation an evolutionary adaptation or social construct? With respect to sexual preferences, to what extent are we "born that way" and to what extent does learning matter? This chapter discusses how nature and nurture may interact to shape sexual motivation by reviewing existing literature on sexual preferences and orientations, as well as by considering sex/gender differences in erotic plasticity, sexual fluidity, and the specificity of sexual arousal.We describe how these phenomena might be accounted for by processes in which mind-body feedback loops amplify some sexual responses over others on multiple levels, which we refer to as the Reward Competition Feedback (RCF) model. With respect to sex/gender differences, we describe how these positive feedback processes might be amplified in men compared with women, potentially substantially driven by differences in the constraints and affordances of female and male anatomy. More specifically, we argue that the well-known female-male difference in the concordance of genital and subjective arousal may contribute to well-known differences in sexual specificity and plasticity/fluidity. We further provide convergent support for RCF by reviewing preexisting theories of sexual learning. Finally, we consider some of the 2 ethical implications of models in which sexual orientation might be shaped by experiences over the course of development.