Intersexuality is a group of medical conditions that blur or make nonstandard the physical sex of the individual intersexual. They include Klinefelter's syndrome (tubule dysgenesis, mostly, though not always correlating to karyotype 47,XXY), congenital adrenal hyperplasia (CAH), androgen insensitivity syndrome (AIS), and many others.

Our culture conceives sex anatomy as a dichotomy: humans come in two sexes, conceived of as so different as to be nearly different species. However, developmental embryology, as well as the existence of intersexuals, proves this to be a cultural construction. Anatomic sex differentiation occurs on a male/female continuum, and there are several dimensions. Genetic sex, or the organization of the "sex chromosomes," is commonly thought to be isomorphic to some idea of "true sex.