So, a strongly patrilineal orientation will be complemented by matrilateral ties with the mother's kin.
Likewise within a strongly matrilineal organisation, patrilateral ties will enter the reckoning of relationships as an important balancing factor.
This complementarity often has a moral or emotional tone to it: Malinowski's classic studies of the matrilineal Trobriand islanders showed that matrilineal ties were associated with discipline and authority, while patrilateral ties were characterised by nurturance and kindness (at least in principle).
Matrilateral cross-cousin marriage is typically used by anthropologists to describe a form of marriage in which the sons of one consanguineous group marry the daughters of the consanguineous group from which their mother originates.
The logical consequences of cross-cousin marriage (matrilateral or patrilateral) for group formation were first discussed in detail by Reo Fortune[1] and have provoked a great deal of debate amongst social anthropologists including Claude Lévi-Strauss, Edmund Leach and Rodney Needham (alliance theory).