Research on differences in sexual orientation and identity.

The human being is sexed, as there are men and women. The presence of two complementary sexes provides a biological mechanism for evolution and adaptation to changing environments through reproduction with the admixture of distinct genetic traits. Ultimately, this reproductive meaning of sex provides its most important biological foundation. In humans, sexuality also plays a significant role in interpersonal relationships and affection, uniquely contributing to personhood, well-being, and flourishing. In this way, both meanings of human sexuality, reproductive and affective, can be challenged in certain scenarios, such as when there are intersex states of biological basis, nowadays referred to as disorders or differences of sex development (DSD), same-sex orientation, or gender dysphoria. Following the approach taken for DSD, same-sex attraction and transgender identity could be categorized medically as differences in sexual orientation and self-identity, respectively. This could provide a respectful framework for conducting research about sexuality. Herein, we examine the spectrum of differences in the sexual sphere and update on major determinants. Whereas biological factors lead to DSD, psychological and sociocultural variables largely contribute to same-sex orientation and transgender identity. Inclusive efforts for persons with atypical sexuality must be encouraged to avoid discrimination. However, these conditions should not be overlooked medically. Denying their relevance might discourage research that would ultimately benefit these individuals.