In humans, sex determination is the process that determines the biological sex of an offspring and, as a result, the sexual characteristics that they will develop. Humans typically develop as either male or female, primarily depending on the combination of sex chromosomes that they inherit from their parents. The human sex chromosomes, called X and Y, are structures in human cells made up of tightly bound deoxyribonucleic acid, or DNA, and proteins. Those are molecules that contain the instructions for the development and functioning of all life forms, including the development of physical traits and body parts that correspond with each biological sex. Humans who inherit two X chromosomes typically develop as females, while humans with one X and one Y chromosome typically develop as males. Sex determination is the beginning of the development of many characteristics that influence how a human looks and functions as well as the societal expectations that other humans have for each other.

In 1938, physician Henry Hubert Turner published “A Syndrome of Infantilism, Congenital Webbed Neck, and Cubitus Valgus,” hereafter “A Syndrome of Infantilism,” in the journal Endocrinology, in which he described a condition that researchers later named Turner syndrome. Turner syndrome is a genetic condition that affects biological females, characterized by a partially or completely missing X chromosome. In the paper, Turner describes a previously unrecognized set of symptoms in seven different females, including a lack of physical and sexual development, infertility, webbed neck, and elbow deformities, among others. Turner also records various methods of hormone treatments for his patients, such as growth hormone and estrogen injections. “A Syndrome of Infantilism” was one of the first published descriptions of Turner syndrome, a developmental condition that affects one in 2,500 live female births globally, and highlighted the use of hormone treatments to promote the development of stunted physical and sexual growth.