What are the motifs in Gender Trouble: Feminism and the Subversion of Identity by Judith Butler?

Much of Gender Trouble is devoted to a genealogy of gender. A 'genealogy' is an attempt to trace the roots of a particular concept not in the development of ideas but through the idea's development due to more materialistic factors, such as economic and social pressures or attempts by some to dominate others; the idea of the genealogy develops partly from Marx and Nietzsche and is wielded with some force by Butler.