Can you cite a problematic outcome of a baby born from an incestuous relationship? Do you have any biology or medical references that describes the problems of incestuous births?I think modern incest laws are also based on biology; specifically, the possible problematic outcomes of babies born to incestuous couples. As an FYI: In the United States the District of Columbia and every state, except Rhode Island, have some form of codified incest prohibition. However, individual statutes vary widely. Rhode Island repealed its criminal incest statute in 1989. Ohio only targets parental figures. New Jersey does not apply any penalties when both parties are 18 years of age or older.
More likely, modern incest laws are based on biblical laws that prohibit incest in order to desexualize the home. That's why biblical law condemns inccest even in the case of adoption, where there is no close genetic relationship.