Sexual differentiation is the process by which individuals develop male or female characteristics, primarily influenced by genetic and hormonal factors. It begins at conception, where the presence of the Y chromosome typically leads to the development of male traits, while the absence of this chromosome results in female traits. During embryonic development, hormones such as testosterone play a crucial role in shaping the reproductive system and secondary sexual characteristics. This differentiation continues through puberty, when physical changes occur, influenced by increased levels of sex hormones like estrogen and testosterone.