This article contends that bloodlines stand as one of the most fundamental yet overlooked aspects of Leopoldo Alas’s seminal work La Regenta. In fact, the narrative begins and ends with the tarnished lineage of Ana Ozores who, over the course of the narrative, wrestles with the conflicting status of her stained origin on the one hand, and her chaste, virtuous temperament on the other. Recovering the discourse of blood, I argue, proves crucial to understanding this conflict. In so doing, this article challenges the conventional periodization that equates blood with the early modern period and sexuality with the modern. Through a critical engagement with Michel Foucault’s History of Sexuality, this article posits blood as the starting point for what I call the “chastity bind,” whereby the ideological underpinnings of limpieza de sangre (purity of blood) thwarts the modern sexual economy that privileges chastity over origin.