Sex determination may refer to: Development of an organism's sex A sex-determination system, a biological system that directs the development of sexual characteristics in an organism Sex determination and differentiation (human) Sexual differentiation, the development of sexual characteristics in sexually reproducing organisms in general Discernment of an organism's sex Prenatal sex discernment, prenatal testing for the discernment of the fetal sex in humans Sex assignment, the discernment of an infant's sex at birth Sexing, used by biologists and agricultural workers to discern the sex of livestock or other animals See also Gender, including biological sex Sexual dimorphism, a phenotypic difference between males and females of the same species, used in sex discernment Sex differences in humans