id="FNanchor_13_13"/>^[13]

CHAPTER II

RATIO OF THE CONSANGUINEOUS TO ALL MARRIAGES

Towards determining the average frequency of occurrence of consanguineous marriages, or the proportion which such marriages bear to the whole number of marriages, little has as yet been done in this country. Professor Richmond Mayo-Smith estimated that marriages between near kin constituted less than one per cent of the total,^[14] and Dr. Lee W. Dean estimates that in Iowa they comprise only about one half of one per cent.^[15] But these estimates are little more than guesses, without any statistical basis.

In several European countries such marriages have been registered, though somewhat spasmodically and inaccurately. According to Mulhall^[16] the ratio of the consanguineous among 10,000 marriages in the various countries is as follows:

According to Uchermann the ratio is 690 or 6.9 per cent, including marriages between second cousins and nearer.^[17] Dr. Peer says that 4 per cent of the marriages in Saxony are consanguineous.^[18] The ratio seems to be increasing in France but diminishing in Alsace and Italy, as indicated in Table II.^[19]

In Italy the ratio varies greatly in different parts of the country. Mulhall gives the following figures for the years 1872-75:

It will be noted that the lowest ratios are in provinces where the urban population is comparatively large. Wherever statistics have been gathered it is the rule that the percentage of consanguineous marriage is greater in rural than in urban districts. Table IV, also from Mulhall, illustrates this point.

In regard to the degree of consanguinity, it seems very probable that in the French, German, Italian, and English statistics and estimates few if any marriages beyond the degree of first cousins are returned as consanguineous, so in order to compare the Norwegian figures with the others they should probably be reduced by one half. Out of 1549 consanguineous marriages contracted in Prussia in 1889, 1422 were between "cousins" (probably first), 110 between uncles and nieces, and 16 between nephews and aunts.^[20] The ratio of such marriages to 10,000 in France during the fifteen years ending in 1875 was:^[21]

In Italy during seven years ending in 1874, of all consanguineous marriages 92 per cent were of cousins and 8 per cent were of uncle and niece or aunt and nephew.