This paper analyzes the discussions in the field of legal medicine in Mexico about the prudence of regulations concerning intermarriage that were decreed in the civil codes for the Federal District of 1871 and 1884. It shows that the heated debate forced the authors of the regulations to struggle for the need for medical vigilance of marriages between relatives, as a preventive measure sustained in a nihilistic vision of the pathological inheritance. The paper concludes by proposing a philosophical analysis that abandons the old fields of the "external" and the "internal".
pathological inheritance; consanguinity; civil rights; Mexico