This research is an empirical and theoretical account of the “born this way” phenomenon as it has developed within the liberal LGBTQ movement in the U.S. It is also a case study in the role that scientific authority can play in the construction of political identities and attendant claims to rights and citizenship. From the 1950s and 1960s homophile and lesbian movement through the present day liberal one, the relationship between researchers and activists developed, multiplied, and deepened as they co-produced understandings of sexuality and gender that drew their legitimacy from scientific authority. Since the early 1970s, intertwining political, legal, and scientific forces have worked together in tandem to construct and deploy increasingly biological theories of identity in venues including laboratories, professional and movement conferences, political campaigns, courtrooms, legislatures, and bureaucracies. This has resulted in the production, popularization, and politicization of bioessentialist renderings of gay, lesbian, bisexual, and transgender identities—i.e. the idea that they are discrete, stable, and relatively innate. These articulations of identity have come to inform and buttress the projects, policies, and ideology of the modern LGBTQ movement. As a result of these alliances between movement actors and their scientific allies, liberal rights claims have become tethered to a narrow biopolitical mode of conceptualizing LGBTQ citizenship. This narrow version of citizenship stems from an ideology of “biologically-linked fate” that offers a limited array of rights to a skewed-segment of the population while constraining the range of what practices and expressions of sexuality and gender identity are deemed worthy of legal protections and social recognition. Though the historical progression of liberal bioessentialism has been punctuated by moments of refusal in the form of New Left gay liberationist and later radical queer suspicions of biomedical authority, the advancement of the born this way idea has been remarkably steady. Through its taxonomizing logic, its privileging of scientific authority for political legitimation, and its hubristic attitude toward what scientific inquiry has proven or can prove, bioessentialist ideology has become a pervasive, influential, and entrenched vision of gender and sexuality in American political culture.