a1 Institute of Population Problems, Ministry of Health and Welfare, Kasumigaseki, Tokyo, Japan
A survey of consanguineous marriages in Japan in couples and their parents was conducted in 1983 through questionnaires. The total number of couples studied was 9225; they were chosen from six widely different areas of the country. The kinship coefficient between parents did not decrease with the year of birth. Thus, the recent decline in the frequency of consanguineous marriages in Japan seems to be largely a post-World War II phenomenon. The kinship decreases with marital distance in the parental generation, and socioeconomic class (level of education and occupation) effects are small by comparison with those of the present generation. The rate of consanguinity is significantly higher in the older generation for almost all areas. The kinship between spouses is less than a half of that in parents for the whole of Japan. Geographical variation in the rate of consanguinity is more remarkable in spouses than parental couples.
(Received June 08 1987)