Oranges are not the Only Fruit is a novel that tells many stories, but ultimately concerns itself with the very act of telling stories. The juxtaposition of legends and myths with the life of the main character, Jeanette, questions the reality of the stories told by the narrators. None of the stories can be verified with any fact, therefore they must all equally be accepted as fictions. It is for this reason that Winterson would say that her novel is not an autobiography. Winterson herself has stated that, "Oranges is the document, both true and false, which will have to serve for my life until I went to Oxford, and after that I daresay that whatever I tell you will be another document, one that is both true and false." As Winterson makes clear with her quote, the truth of the life of Jeanette is not true at all. As Winterson took pains to express in Chapter Five, no stories or histories are ever wholly true because subjective writers have written them. Winterson forces the realization that no objective reality exists anywhere. Whenever reality is represented by an art form, the realness of the reality must be called into question because it has been subjectively framed.
The idea that Jeanette is on a mythic journey thematically frames her narrative. Jeanette's birth and adoption are described with images from the story of Christ. From an early age, Jeanette believes that she will emerge as a Christlike figure who will help to save the world. As she ages, however, it becomes clear that her true quest is simply to find and accept her self. This task is not an easy, however. Jeanette's homosexual desires contradict the regulations that she has believed all of her life. To accept who she truly is, Jeanette must embark on a physical and spiritual adventure. She must both leave her home and leave her assumptions of how the world and her self are defined. Winterson borrows the standard techniques from a mythic story for Jeanette's adventure. Winterson also places other mythic characters in the novel, such as Sir Perceval, to place Jeanette's story in the mythic realm. Although Jeanette's adventure requires that she venture outside of the normative heterosexual sphere, her quest still takes the standard steps. From her birth Jeanette was destined for a mission and by the end of the novel it becomes clear that even though she has become a lesbian, her quest still continues. Even as a writer and a lesbian, Jeanette can still help to fight against the evil in the world as her mother originally intended.
An overriding theme in the novel concerns the conflict between binary factors. Jeanette's mother can only see the world as good or evil, friend or foe. Yet, Jeanette's homosexuality places her outside of the binary by showing that she is neither wholly good nor wholly evil. At the same time, Jeanette's lesbianism defies the binary gender roles that traditionally dominate society. Jeanette is a woman who does not act as a traditional woman because she does not love men. Winterson takes pains to illustrate the shifting nature of genders by switching some of gender roles in her mythical tales. She, like other postmodern feminists such as Julia Kristeva and Monique Wittig, proposes that the concept of gender is socially constructed, not biologically inherent. Overall, the construction of the world in binary systems limits and excludes those people and stories that fall outside of the definitions. By not seeing the world as a strict duality, a greater multiplicity of people can be seen as creating its essence. People are not simply black and white, but also line the many shades of gray in between.