Drawing on Judith Butler’s idea of gender as a cultural construct imposed on people through mimicking, imitation or what Butler calls “performance”, this paper seeks to emphasise the theme of impersonation and stolen identities in Mary Morrissy’s novels Mother of Pearl and The Pretender. In each of these novels, Morrissy interrogates the issue of identity, which reveals to be contingent, flexible and unstable instead of permanently fixed, as is evidenced by the way it can be imposed upon a person, or stolen or borrowed. Mother of Pearl in particular problematises women’s assigned biological destinies by focusing on motherhood, in the way it stages female characters suffering from a defective bond with their mothers. The structure of the narrative is built around a female genealogy which proves to be thoroughly dysfunctional and contaminating instead of nurturing and constructive. The division of the novel into three parts, each of which is devoted to a different female character – Irene, Rita and finally Pearl – enables Mary Morrissy to offer three different versions of gender performance, especially regarding motherhood. It also gives the impression that each of the characters’ fragment of individual story combines with the others to make up one continuous narrative, which blurs the outlines of each separate identity. Mary Morrissy’s second novel The Pretender takes up the same notion of a troubled identity and of the acting out of various possible roles for a woman to play. Based on the true story – as was Mother of Pearl – of Anna Anderson, who pretended to be Tsar Nicolas II’s daughter Anastasia, the novel suggests that gender identity is only a fiction imposed upon us, and especially on women, a fiction which can be exposed by replacing it with any other, by introducing “a variation in the repetition of the performance of gender” as Butler would have it.