All human groups have a kinship terminology, a set of terms used to refer to kin. The study of kinship is the greatest common denominator across the different fractions of social anthropology. The first scientific study of kinship was conducted by Lewis Henry Morgan and reported in the work entitled: "Systems of Consanguinity and Affinity of the Human Family" (1870) (Fischer, 2001) The work entitled: "The Anthropology of Kinship" states that social groups based upon matrifiliation are social groups in which membership is: "recruited through mothers" (Parkin, 2004) with the rationalization being a model of conception that appoints the father little if any role in the conception of a child. Filiation and descent groups are stated to: "...continue to play an important role in determining social behavior today throughout the world." (Parkin, 2004) Stated as well in the work of Parkin (2004) is the fact that:

some form of sexual regulation, found either in the form of laws or taboos, is universal. One common regulation is a prohibition of sexual intercourse between relatives." (Parkin, 2004)

However it is noted by Parkin that a variation exists from one society to another and over time as to which relatives are those forbidden to have sex with one another. Major is a major social mechanism within society and various structures within various societies cause a variation in the affects of marriage within that specific society.

The work of Parkin (2004) points out the fact that:

there were at one time a complex set of social norms defining appropriate relationships between African- and European-Americans. A male of European descent was forbidden to marry a female of African descent but sex between the two was permitted. The rules were different for a female of European descent and a male of African descent. Neither marriage nor intercourse was tolerated. In a very different case from northern...

Other reasons for regulation of sexual relations are due to religious beliefs, societal and military alliances, and other conceived morality issue within a cultural group or society. This work has reviewed the factors of 'exogamy' and 'endogamy' in the cultural group sexual regulations and as well as has stated several different cultural regulations of sexual activity in various cultures throughout the world.
Bibliography

Kittelson, a. And Stafford, a. (nd) Yanomamo. MSU. Online available at http://www.mnsu.edu/emuseum/cultural/southamerica/yonomamo.html

Schwimmer, B. (1998) Intergroup Relations and Social Distance among the Yanomamo. Online available at http://umanitoba.ca/faculties/arts/anthropology/tutor/case_studies/yanomamo/soc_dist.html.

Schwimmer, B. (1998) Marriage Systems. Online available at http://umanitoba.ca/faculties/arts/anthropology/tutor/marriage/intro.html.

Sexual Relations among Young People in Developing Countries (2001) World Health Organization. Online available at http://www.who.int/reproductive-health/publications/RHR_01_8/index.html.

Parkin, Robert J. (2004) the Anthropology of Kinship. Blackwell Anthologies in Social & Cultural Anthropology.

Fischer, Michael D. (nd) Representing Anthropological Knowledge: Calculating Kinship - Analyzing and Understanding Cultural Codes. Online available at http://www.era.anthropology.ac.uk/Kinship/kinIntro.html.

Social Organization & Social Systems: Societal Regulation