Population structure in Norway Inbreeding, distance and kinship

Total and local general inbreeding coefficients of the Norwegian population have been calculated from data of the 1891-census (1860–1890 marriages) and 1903–1941 marriage contraction protocols. The 19th century data covered up to second cousin marriages (Ucher-mann 1896), and the partially extracted 20th century data all first cousin marriages (Herlof-sen 1961). The totally extracted data from 1905 revealed the 1 : 1 ratio of first to second cousin marriages. General inbreeding decreased from α4 = .00260 to α4 = .00028 over two generations, and showed significant urban/rural and local rural heterogeneity. The distance-distribution of random pairs and of mating pairs of Norwegians have been studied by means of the DISTAN computor program, revealing a rough approximation to the augmented gamma distribution for distance in kilometers. For mating pairs a better approximation was found for distance measured by a municipality COUNT method. In the “random” mating-pair material inbreeding from pedigree had a distance distribution deviating somewhat from the expectancy for random inbreeding = kinship according to the Malécot theory, suggesting preferential consanguineous marriages to have a skew distance distribution. No good estimate of kinship was therefore obtained. The distance distributions of first cousin matings, and of pairs heterozygous for rare recessive genes, were studied. Potentially informative for kinship, the latter material could not be analysed due to lack of suitable control matings. Sufficient information on random pair distance in Norway is now collected to make future assays of kinships from polymorphs (blood-, serum- and enzyme-types) or metrics easy and fruitful.