In a controlled study of Mafia marriages in Corleone, I find evidence supporting the hypothesis that Mafia members are more closely related to their brides than their non-mafiosi neighbors in Corleone.
On average, Mafia members and their wives in this study are more than twice as closely related as the control group grooms and their brides.
Average coefficient of relationship and rate of consanguineous marriage
|Average coefficient of relationship between bride and groom, out to fourth cousins||Percent of marriages that are consanguineous in this set, out to third cousins|
The differences in marital consanguinity between the two groups are pronounced. Compared to the control group, Mafia couples are almost three times as likely to have a close degree of kinship: third cousins or closer, which is to say, having in common at least one set of twice-great grandparents or a nearer direct ancestor.
Although the coefficient of relationship (CoR) of the control group, on average, is less than half of the average CoR for the Mafia group, the difference between these two figures is slight, in genealogical terms. A coefficient of relationship of 0.008, the average for Mafia couples in this study, is between that of a fourth cousin, once removed (0.1) and the CoR of fifth cousins (0.0004). (See the table in Part 1.) This is as good an illustration as any, of the practicality of researching only three or four generations to determine CoR. The decrease in CoR is exponential, and becomes vanishingly small beyond the degree of fourth cousins.
Relationships more distant than fourth cousins are not included in calculations of average CoR or in the percentage of consanguineous marriages. One Mafia marriage (Marco Maggiore, 1908) is between fifth cousins, and one marriage from each set, the Mafia group and the control group, are between fifth cousins, once removed (Giuseppe Morello, 1903, and Giuseppe Verro, 1902).
Out of the 35 marriages of Mafia members (named in Part 2), five are consanguineous. Nicolo’ Ciravolo and his second wife (married in 1834) are third cousins. Paolino Streva married his first cousin, once removed, in 1894, as did Antonino Cascio in 1906. Luciano Labruzzo and his wife, who married in 1897, are in a double in law marriage and are both first and third cousins, for a CoR of 13.28%. Luciano Gagliano (1880) and Carlo Taverna (1904) are also in double in law marriages, though not related by common ancestry to their wives. Luciano Crapisi, who married in 1880, is related to his wife three different ways: they are fourth cousins, fifth cousins, and fifth cousins, once removed, for a CoF of .20%.
Among the 35 control marriages, the most closely related are Salvatore Pomilla (1893) and his wife, who are are first cousins, once removed. Carmelo d’Anna and his wife (1880) are both second and third cousins. Calogero Pecoraro marries twice, to sisters who are his third cousins, once removed. If Calogero had children with each of his wives, they would be more closely related than typical half-siblings, with a CoR of 37.5%.
Next week, a discussion of the implications of this research.
Feature image: Interior of Monreale Cathedral, by Bernhard J. Scheuvens aka Bjs [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5)%5D, via Wikimedia Commons