Towards a complete North American Anabaptist genealogy II. Analysis of inbreeding

We describe a large genealogy data base, which can be searched by computer, of 295,095 Amish and Mennonite individuals. The data base was constructed by merging our existing Anabaptist Genealogy Database 2.0 containing approx imately 85,000 individuals with a genealogy file containing approximately 2 42,000 individuals, kindly provided by Mr. James Hostetler. The merging pro cess corrected thousands of inconsistencies and eliminated hundreds of dupl icate individuals. Geneticists have long been interested in Anabaptist popu lations because they are closed and have detailed written genealogies. The creation of an enlarged and unified data base affords the opportunity to ex amine inbreeding trends and correlates in these populations. We show the fo llowing results. The frequency of consanguineous marriages shows steady inc rease over time and reached approximately 85% for individuals born in 1940- 1959. Among consanguineous marriages, the median kinship coefficient stayed stable in the 19th century, but rose from 0.0115 to 0.0151 in the 20th cen tury. There are statistically significant associations (p < 0.0001) between inbreeding and family size and interbirth intervals in the 20th century. T here is an association (p < 0.0005) between inbreeding and early death for individuals born in 1920-1959. However, this association reverses dramatica lly (p < 0.0005 in the opposite direction) for individuals born in 1960-197 9, We tested for an association between inbreeding and being the mother of twins, but found none.