There is controversy regarding participation in high profile competitive events by female athletes perceived as inappropriately “masculine” by competitors and others. Over 50 years, international sports bodies such as the International Olympic Committee (IOC) and the International Association of Athletics Federations (IAAF) employed - and ultimately discarded - various procedures to ensure feminiity. Though ostensibly to detect male imposters, in practice these identified women with genetic Disorders of Sex Development (DSD), such as androgen insensitivity syndrome, complete or partial; 5 alpha-reductase deficiency; mixed gonadal dysgenesis. Further, increased participation in women's sport has vastly enlarged the competitive field and the probability of athletes with a DSD competing.
Do female athletes with a DSD have any “unfair” competitive advantage, especially since specific genetic endowment provides advantage to excel in specific events? This “endowment” can include recognized medical disorders such as height in Marfan Syndrome and delayed maturation and short stature in gonadal dysgenesis, even simple genetic variation such as more fast or slow twitch muscle fibers. A Finnish athlete with exceptional success in endurance Nordic skiing was found to have high hemoglobin and increased oxygen carrying capacity due to an inherited mutation in the erythropoietin receptor; similar mutations occur world wide. Even longer toes are associated with greater “lift-off” and success in sprint events.
Thus the ideal of a “level playing field” is illusory and fundamentally women with some DSDs have no more competitive advantage than other elite athletes with favorable genetic characteristics.