Repetition of the same pair of surnames in marriages in Albanian Italians, Greek Italians, and the Italian population of Campobasso Province.

The isolation of a population as a result of any boundary leads to a kinship mating pattern, the extent of which can be measured by the frequency of repeated pairs of surnames in actual marriages compared with that in random pairings. The repeated pairs within surname lineages (RPw) method can be used to assess random repetitions and the endogamous or exogamous behavior of a population. The RPw method was applied to data from grandparent surnames of children living in 45 Albanian Italian and 13 Greek Italian villages of southern Italy and Sicily and in 22 Italian villages of Campobasso Province (central Italy). The total mean RPw was 0.02782 in Albanian Italians, 0.01993 in Greek Italians, and 0.03427 in the Italian-speaking population. When RPw was subdivided into its components and compared with random and marital isonymy, the low level of inbreeding shown by the two southern Italian ethnic minorities and by the Italian population of Campobasso Province could be accounted for by the subdivision of the populations.