Endogamy and Exogamy

Abstract

While a rapid increase in mating between ethnic groups has been noted in the United States in the past twenty years, few studies have been made on the consequences of out‐crossing. This report conveys findings on the interrelationships of three factors: fetal loss, number of countries in the background of parents, and the distances between birthplaces of parents. Data show that fetal loss in matings of the parental generation increases cumulatively by some 2.5% to 3% with each additional country of birth in the great‐grandparental generation. Increased fetal loss is also related to greater distances between birthplaces of mates within the parental generation. Low fetal loss is found with a small number of countries in the background and shorter distance between birthplaces. It is suggested that a larger number of countries of birth represents a larger number of Mendelian gene pools and that with increased mixture of these gene pools, fetal loss increases proportionately. An animal model is cited in support of this contention.