This chapter delves into the biological, psychological, and social factors influencing male sexual orientation. It covers theories of sexual identity development, neurobiological correlates, and the distinction between orientation, behavior, and identity. Clinical relevance includes counseling, nonjudgmental care, and understanding sexual diversity in andrology and sexual medicine. Contemporary andrological and endocrinological frameworks recognize sexual orientation and gender identity as biologically influenced yet non-pathological variations of human sexuality. In particular, the XYGO framework highlights the role of sex chromosome–related gene expression and neurodevelopmental pathways in shaping sexual orientation, consistent with recent European Academy of Andrology–aligned perspectives.