Sex and gender distinction
Sex is distinct from gender, which can refer to either social roles based on the sex of a person (gender role) or personal identification of one's own gender based on an internal awareness (gender identity). While in ordinary speech, the terms sex and gender are often used interchangeably, most contemporary social scientists, behavioral scientists and biologists, many legal systems and government bodies, and intergovernmental agencies such as the WHO make a distinction between gender and sex.
In most individuals, the various biological determinants of sex are congruent, and consistent with the individual's gender identity, but in some circumstances, an individual's assigned sex and gender do not align, and the person may be transgender. In other cases, an individual may have sex characteristics that complicate sex assignment, and the person may be intersex.
Sexologist John Money is often regarded as the first to introduce a distinction between biological sex and gender identity/role in 1955, although Madison Bentley had already defined gender as the "socialized obverse of sex" a decade earlier. As originally conceived by Money, gender and sex are analysed together as a single category including both biological and social elements, but later work by Robert Stoller separated the two, designating sex and gender as biological and cultural categories, respectively. Before the work of Bentley, Money and Stoller, the word gender was only regularly used to refer to grammatical categories.