<P> Sex verification in sports (also known as gender verification, or loosely as gender determination or a sex test) is the issue of verifying the eligibility of an athlete to compete in a sporting event that is limited to a single sex . The issue has arisen multiple times in the Olympic games and other sporting competitions where it has been alleged that male athletes attempted to compete as women, or that a woman has an intersex condition giving an alleged unfair advantage . </P> <P> The first mandatory sex test issued by the IAAF for woman athletes was in July 1950 in the month before the European Championships in Belgium . All athletes were tested in their own countries . Sex testing at the games began at the 1966 European Athletics Championships in response to suspicion that several of the best women athletes from the Soviet Union and Eastern Europe were actually men . At the Olympics, testing was introduced in 1968 . </P> <P> Initially, sex verification took the form of physical examinations . It subsequently evolved into chromosome testing, and later testosterone testing . It is not always a simple case of checking for XX vs. XY chromosomes, or sex hormone levels, to determine whether an athlete is unambiguously a woman or a man . Fetuses start out as undifferentiated, and the Y chromosome turns on a variety of hormones that differentiate the baby as a male . Sometimes this does not occur, and 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 . </P>

When did gender testing of female olympic athletes begin