Caster Semenya, an 18-year-old woman from South Africa, is considered the favorite in the upcoming 800m World Athletics Championships race. But might Semenya have an unfair competitive advantage because she is actually a he? On Wednesday race officials revealed that they had ordered Semenya to take a gender test, though the results have not yet been confirmed. Semenya's unusually muscular physique, along with her stunning performance in a previous 800m race in which she smashed a world record by more than one second, raised skepticism. According to the Daily Mail, some experts were "concerned with the way she runs," (though it is unclear exactly what about her running style arouses suspicion). Pending results of the test, Semenya will be participating in the race on Wednesday. If she does turn out to be a man, she would be following in a long line of athletes who tried to dupe their way into the record books by posing as women.