Nara Milanich is a historian at Barnard College specializing in Latin America and the comparative histories of family, childhood, gender, and reproduction. She is the author of Paternity: The Elusive Quest for the Father, published by Harvard University Press, which will be released in time for Father’s Day (June 2019). The book tells the story of the transatlantic quest to find a scientific proof of paternity over the course of the twentieth century. But while the science of heredity promised to solve the problem of the unknown father, paternity has always been less a biological riddle than a social and political one.