ABSTRACT
This chapter discusses the varying sexual understandings, including transgender identity, ambiguous sex organs and chromosomes, twin studies, the role of hormones, epigenetic and a cautionary tale about medical intervention. All psychological and physiological dimensions of life interact in human sexuality including biology, cognition and emotion. Although biology plays a major role in human sexuality, there are also habitual ways of thinking and social norms that determine the acceptability of both heterosexuality and homosexuality. All important psychological and physiological dimensions of life interact in human sexuality. The Western world has experienced large changes in sexual norms and behaviour. The scientific study of sexuality commenced with the studies by A. C. Kinsey on the sexual practices of US men and women. W. H. Masters and V. E. Johnson were the researchers to actively investigate sexuality by observing the responses of human volunteers in their laboratory. In the excitement phase, the partners become responsive to sexual imagery and touching during foreplay.
