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Discovery[ edit ] The Y chromosome was identified as a sex-determining chromosome by Nettie Stevens at Bryn Mawr College in during a study of the mealworm Tenebrio molitor. Edmund Beecher Wilson independently discovered the same mechanisms the same year. Stevens proposed that chromosomes always existed in pairs and that the Y chromosome was the pair of the X chromosome discovered in by Hermann Henking. She realized that the previous idea of Clarence Erwin McClung , that the X chromosome determines sex, was wrong and that sex determination is, in fact, due to the presence or absence of the Y chromosome.
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