<p><span>Birth certificates are the subject of fierce debate. This conflict is most visible in battles over gender markers for transgender people. Less visible, but no less consequential, are debates over parentage designations on birth certificates—that is, listing the names of a child’s parents. Arguments rooted in biology, which feature in both contexts, can reflect, justify, and perpetuate inequality. This insight is appreciated in the debate over gender markers but has been largely overlooked in debates about parentage.</span></p> <p><span>The birth certificate’s role in recording a child’s legal parents has been critical to protecting families long subject to exclusion and discrimination—from efforts to dismantle the stigma of “illegitimacy” to challenges to the discriminatory treatment of children of LGBTQ parents. Today, however, a growing number of proposals call for children’s birth certificates to list people who are biological but nonlegal parents. These proposals, which emerge from both the right and the left, have yet to attract significant scholarly skepticism. Proponents of these efforts suggest that the identification of biological parent-child ties is natural, neutral, and benign and consistent with “common understandings” of these documents. But assessing these “reform” efforts requires a clearer understanding of what birth certificates are, how they function, and how they have evolved to reflect both the changing legal status of the family and emergent equality principles.</span></p> <p><span>This Article offers the first comprehensive account of the <span>history, function, and contemporary regulation of parentage designations on birth certificates. We show that </span>the proposals on offer do not find support in the history of birth certificates. Nor do they reflect current practices and policies regarding birth certificates. Instead, if embraced, they would fundamentally alter what birth certificates are and how they function.</span></p> <p><span>T</span><span>his Article uncovers the far-reaching normative and ideological implications of having birth certificates record “biological parents.” <span>G</span>iven the role that birth certificates play (and long have played) as critical legal identity documents, this move would inflict significant legal harms on families with nonbiological parent-child relationships as they navigate everyday life—from traveling to accessing healthcare. Arguments in favor of birth certificate “reform” also naturalize and valorize a certain family form—the marital, heterosexual, gender-differentiated family—and denigrate others—including LGBTQ families, families formed through assisted reproduction, and adoptive families. In the end, proposals to remake birth certificates into records of biological facts would reinscribe the very exclusions and inequalities that our legal system has rightly repudiated.</span></p>