Table 1.

A summary of kinship and fertility in 25-year intervals from 1800 to 1965. Shown are descriptive statistics for kinship coefficients and three variables that reflect the completed fertility (the total number of offspring) and reproductive success (the total number of children who reproduce and the total number of grandchildren) of the couples.

All couplesCouples with qΦ > 0
Birth year of female N Mean qΦ (SE)* Mean number of offspring per couple (SE) Mean number of offspring that reproduce per couple (SE) Mean number of grandchildren per couple (SE) N Mean kinship Φ × 1000 (25-75 percentiles)
1800-1824 8,673 0.426 (0.0021) 3.610 (0.0359) 1.765 (0.0195) 7.901 (0.1051) 8,362 4.93 (0.004-1.012)
1825-1849 14,338 0.514 (0.0013) 3.468 (0.0254) 1.639 (0.0146) 7.384 (0.0768) 14,109 5.45 (0.029-1.195)
1850-1874 15,863 0.606 (0.0011) 3.221 (0.0234) 1.749 (0.0157) 7.193 (0.0733) 15,575 4.76 (0.054-1.257)
1875-1899 16,691 0.672 (0.0012) 3.392 (0.0231) 2.430 (0.0180) 9.053 (0.0758) 16,268 3.70 (0.043-1.050)
1900-1924 24,732 0.721 (0.0011) 2.791 (0.0143) 2.360 (0.0127) 7.467 (0.0450) 23,799 2.01 (0.024-0.562)
1925-1949 39,635 0.759 (0.0010) 2.547 (0.0087) 1.996 (0.0083) 4.983 (0.0237) 37,762 0.82 (0.022-0.336)
1950-1965 40,879 0.782 (0.0012) 2.004 (0.0058) 0.501 (0.0038) 0.864 (0.0075) 38,336 0.50 (0.033-0.306)
Total 160,811 0.695 (0.0005) 2.740 (0.0058) 1.648 (0.0046) 5.330 (0.0182) 154,211 2.22 (0.029-0.526)
  • * qΦ is a weighted measure of the genealogical information available to calculate the kinship of couples, with values between 0 (when at least one spouse has no known ancestor) and 1 (when all ancestors are known for both spouses). See (10) for more details.