How do you know if you are transgender? How do you know if what you want and feel is real? How do you know whether to believe yourself? Cyrus Dunham’s life always felt like a series of imitations—lovable little girl, daughter, sister, young gay woman. But in a culture of relentless self-branding, and in a family subject to the intrusions and objectifications that attend fame, dissociation can come to feel normal.