One of the most endogenous societies in the world, Japan has approved of incestuous marriages in court circles even in historical times.(152) Preferred sibling, cousin, uncle-niece and aunt-nephew marriages have been so extensive that genetics experts have discovered that the inbreeding has affected their size and health.(153) How often this incestuous marriage system occurred in traditional Japan is still largely unexplored. One indication of what is likely to be found is a 1959 study by Kubo showing that there were still rural areas in Japan where fathers married their daughters when the mother had died or was incapacitated, "in accordance with feudal family traditions.(154) Kubo concluded that incest was considered "praiseworthy conduct" in many traditional rural families. In the 36 incest cases he studied in Hiroshima, he found that there was often community moral disapproval of the families who lived in open incestuous marriages, but that the participants themselves did not think of it as immoral. In fact, when the father was unavailable to head the family, his son often took over his role and had sex with his sister in order "to end confusion in the order of the home." Other members of the family accepted this incest as normal.
