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In the late 1980 s , Judith Butler began lecturing regularly on the topic of gender identity , and in 1990 , she published " Gender Trouble : Feminism and the Subversion of Identity " , introducing the concept of gender performativity and arguing that both sex and gender are constructed .
 Judith Butler, Gender Trouble : Feminism and the Subversion of Identity
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 Judith Butler, Gender Trouble : Feminism and the Subversion of Identity