the SRY gene (which is usually—but not always—located on the Y chromosome) turns on a variety of hormones that differentiate by the time of birth the newborn as a male baby. But sometimes this differentiation does not occur while other times the SRY gene is located on a different chromosome: People with two X chromosomes can develop hormonally or phenotypically as a male; and people with an X and a Y can develop hormonally or phenotypically as a female. Physical examinations United States Olympic Committee president Avery Brundage requested, during or shortly after the 1936 Summer Olympics in Berlin, that a system be established to examine female athletes. According to a Time magazine article about hermaphrodites, Brundage felt the need to clarify "sex ambiguities" after observing the performance of Czechoslovak runner and jumper Zdeňka Koubková and English shotputter and javelin thrower Mary Edith Louise Weston. Both individuals later had gender reassignment surgery and legally changed their names, to Zdeněk Koubek and Mark Weston, respectively. Sex verification tests began in 1950 with the International Association of Athletics Federations (IAAF), using physical examinations. "Sex segregation and verification are mutually interdependent because, if there were no claims or basis for having separate male and female sporting events, there would be no need for sex verification testing." The Dutch athlete Foekje Dillema was banned for life in July 1950. The International Olympic Committee followed suit in 1968. Initially, women athletes "were asked to parade nude before a panel of doctors". For a period of time these tests were mandatory for female athletes, due to fears that male athletes would pose as female athletes and have an unfair advantage over their competitors. Chromosome testing Chromosome testing was introduced by the International Olympic Committee during the 1968 Summer Olympics. This tested for the Y-chromosome, and was designed to identify males potentially disguised as females. This method of testing was later abolished, as it was shown to be inconclusive in identifying maleness. The International Association of Athletics Federations ceased sex screening for all athletes in 1992, but retained the option of assessing the sex of a participant should suspicions arise. A resolution was passed at the 1996 International Olympic Committee (IOC) World Conference on Women and Health "to discontinue the current process of gender verification during the Olympic Games". The International Olympic Committee's board voted to discontinue the practice in June 1999. Chromosome testing was last performed