Cross-cousin
Cross-cousin, the child of oneās motherās brother or fatherās sister. Scholars of kinship distinguish the different types of first cousin as follows: the children of a fatherās siblings are patrilateral cousins, and those of a motherās siblings are matrilateral cousins; the children of a motherās sister or of a fatherās brother are parallel cousins (sometimes called ortho-cousins); and the children of a fatherās sister or of a motherās brother are cross-cousins.
Whereas the English word cousin covers all of these relationships, many languages place parallel cousins and cross-cousins in separate categories; in such cases, the terms used to denote parallel cousins are frequently the same as those denoting siblings. A smaller group of languages places the parallel cousins in one category but distinguishes the patrilateral cross-cousins from the matrilateral cross-cousins. Still another group of languages uses separate words for each of the four possible kinds of cousins: patrilateral cross-cousins, patrilateral parallel cousins, matrilateral cross-cousins, and matrilateral parallel cousins.
Some societies consider first-cousin marriages to be ideal. In those that differentiate between cross-cousins and parallel cousins, cross-cousin marriage is usually preferred or sometimes even obligatory, while marriage between parallel cousins often falls under incest taboos. In exceptional cases, however, the opposite is true. Even when a cross-cousin is the preferential mate, actual instances of such marriages in a given society may be small, for such decisions are also influenced by local customs governing succession, inheritance, and residence. Cross-cousin marriage often acts as a device to strengthen alliances between clans.