When referring to their cousins, people in the United States generally do not differentiate between types of cousins. In some other societies, such distinctions can be important, particularly with regard to first cousins. The terms for the different kinds of first cousins may indicate which cousins are suitable marriage partners (sometimes even preferred mates) and which are not. Although most societies prohibit marriage with all types of first cousins,78 some societies allow and even prefer particular kinds of cousin marriage.
When first-cousin marriage is allowed or preferred, it is usually with some kind of cross-cousin. Cross-cousins are children of siblings of the opposite sex; that is, a person’s cross-cousins are the father’s sisters’ children and the mother’s brothers’ children. The Chippewa Indians used to practice cross-cousin marriage, as well as cross-cousin joking. With his female cross-cousins, a Chippewa man was expected to exchange broad, risqué jokes, but he would not do so with his parallel cousins, with whom severe propriety was the rule.
Parallel cousins are children of siblings of the same sex; a person’s parallel cousins, then, are the father’s brothers’ children and the mother’s sisters’ children. In general, in any society that allows cross-cousin but not parallel-cousin marriage, a joking relationship exists between a man and his female cross-cousins. In marked contrast, the man will maintain a formal and respectful relationship with female parallel cousins. The joking relationship apparently signifies the possibility of marriage, whereas the respectful relationship extends the incest taboo to parallel cousins.
Parallel-cousin marriage is fairly rare, but some Muslim societies have historically preferred such marriages and allowed other cousin marriages as well. The Kurds, who are mostly Sunni Muslims, preferred that a young man marry his father’s brother’s daughter (for her part, the young woman would be marrying her father’s brother’s son). The woman will stay close to home in such a marriage, since her father and his brother usually live near each other. Because the bride and groom are also in the same kin group, marriage in this case also entails kin group endogamy.79
What kinds of societies allow or prefer first-cousin marriage? There is evidence from cross-cultural research that cousin marriages are most likely to be permitted in relatively large and densely populated societies. Perhaps this is because such marriages, and thus the risks of inbreeding, are less likely in large populations. However, a number of small, sparsely populated societies also permit or even prefer cousin marriage. How can these cases be explained? It appears that most of the small societies that permit cousin marriage have lost a lot of people to epidemics. For example, many societies around the world, particularly in the Pacific and in North and South America, suffered severe depopulation in the first generation or two after contact with Europeans, who introduced diseases (including measles, pneumonia, and smallpox) to which the native populations had little or no resistance. Such societies may have permitted cousin marriage to provide enough mating possibilities within a reduced population of eligible mates.80