Family denotes a group of people affiliated by consanguinity, affinity, or co-residence. Although the concept of consanguinity originally referred to relations by "blood," many anthropologists have argued that one must understand the notion of "blood" metaphorically, and that many societies understand 'family' through other concepts rather than through genetic distance. Many sociologists and anthropologists believe the primary function of the family is to perpetuate society, either biologically, socially, or both. Thus, one's experience of one's family shifts over time. From the perspective of children, the family is a family of orientation: the family serves to locate children socially, and plays a major role in their enculturation and socialization. From the point of view of the parent(s), the family is a family of procreation the goal of which is to produce and enculturate and socialize children. However, producing children is not the only function of the family; in societies with a sexual division of labor, marriage, and the resulting relationship between two people, is necessary for the formation of an economically productive household.
A conjugal family consists of one or more mothers and their children, and/or one or more spouses, usually husbands. The most common form of this family in the western world is regularly referred to as a nuclear family.
A consanguineal family consists of a mother and her children, and other people — usually the family of the mother, like her husband. This kind of family is common where mothers do not have the resources to rear their children on their own, and especially where property is inherited. When important property is owned by men, consanguineal families commonly consist of a husband and wife, their children and other members of the husband's family.
A matrifocal family consists of a mother and her children. Generally, these children are her biological offspring, although adoption of children is a practice in nearly every society. This kind of family is common where women have the resources to rear their children by themselves, or where men are more mobile than women.
Anthropologists have often supposed that the family in a traditional society forms the primary economic unit. This economic role has gradually diminished in modern times, and in societies like the United States it has become much smaller — except in certain sectors such as agriculture and in a few upper class families. In China the family as an economic unit still plays a strong role in the countryside. However, the relations between the economic role of the family, its socio-economic mode of production and cultural values remain highly complex.
Morgan made a distinction between kinship systems that use classificatory terminology and those that use descriptive terminology. Morgan's distinction is widely misunderstood, even by contemporary anthropologists. Classificatory systems are generally and erroneously understood to be those that "class together" with a single term relatives who actually do not have the same type of relationship to ego. (What defines "same type of relationship" under such definitions seems to be genealogical relationship. This is more than a bit problematic given that any genealogical description, no matter how standardized, employs words originating in a folk understanding of kinship.) What Morgan's terminology actually differentiates are those (classificatory) kinship systems that do not distinguish lineal and collateral relationships and those (descriptive) kinship systems which do. Morgan, a lawyer, came to make this distinction in an effort to understand Seneca inheritance practices. A Seneca man's effects were inherited by his sisters' children rather than by his own children. Morgan identified six basic patterns of kinship terminologies:
Most Western societies employ Eskimo kinship terminology. This kinship terminology commonly occurs in societies based on conjugal (or nuclear) families, where nuclear families have a degree of relatively mobility.
Members of the nuclear family (or immediate family) use descriptive kinship terms:
Such systems generally assume that the mother's husband has also served as the biological father. In some families, a woman may have children with more than one man or a man may have children with more than one woman. The system refers to a child who shares only one parent with another child as a "half-brother" or "half-sister". For children who do not share biological or adoptive parents in common, English-speakers use the term "stepbrother" or "stepsister" to refer to their new relationship with each other when one of their biological parents marries one of the other child's biological parents. Any person (other than the biological parent of a child) who marries the parent of that child becomes the "stepparent" of the child, either the "stepmother" or "stepfather". The same terms generally apply to children adopted into a family as to children born into the family.
Typically, societies with conjugal families also favor neolocal residence; thus upon marriage a person separates from the nuclear family of their childhood (family of orientation) and forms a new nuclear family (family of procreation). This practice means that members of one's own nuclear family once functioned as members of another nuclear family, or may one day become members of another nuclear family.
Members of the nuclear families of members of one's own (former) nuclear family may class as lineal or as collateral. Kin who regard them as lineal refer to them in terms that build on the terms used within the nuclear family:
For collateral relatives, more classificatory terms come into play, terms that do not build on the terms used within the nuclear family:
When additional generations intervene (in other words, when one's collateral relatives belong to the same generation as one's grandparents or grandchildren), the prefix "grand" modifies these terms. (Although in casual usage in the USA a "grand aunt" is often referred to as a "great aunt", for instance.) And as with grandparents and grandchildren, as more generations intervene the prefix becomes "great grand", adding an additional "great" for each additional generation.
Most collateral relatives have never had membership of the nuclear family of the members of one's own nuclear family.
Cousins of an older generation (in other words, one's parents' first cousins), though technically first cousins once removed, often get classified with "aunts" and "uncles".
Similarly, a person may refer to close friends of one's parents as "aunt" or "uncle", or may refer to close friends as "brother" or "sister", using the practice of fictive kinship.
English-speakers mark relationships by marriage (except for wife/husband) with the tag "-in-law". The mother and father of one's spouse become one's mother-in-law and father-in-law; the female spouse of one's child becomes one's daughter-in-law and the male spouse of one's child becomes one's son-in-law. The term "Sister-in-law" refers to three essentially different relationships, either the wife of one's sibling, or the sister of one's spouse, or the wife of one's spouse's sibling. "Brother-in-law" expresses a similar ambiguity. No special terms exist for the rest of one's spouse's family.
The terms "half-brother" and "half-sister" indicate siblings who share only one biological or adoptive parent.
The different types of families occur in a wide variety of settings, and their specific functions and meanings depend largely on their relationship to other social institutions. Sociologists have a special interest in the function and status of these forms in stratified (especially capitalist) societies.
The term "nuclear family" is commonly used, especially in the United States and Europe, to refer to conjugal families. Sociologists distinguish between conjugal families (relatively independent of the kindreds of the parents and of other families in general) and nuclear families (which maintain relatively close ties with their kindreds).
The term "extended family" is also common, especially in the United States and Europe. This term has two distinct meanings. First, it serves as a synonym of "consanguinal family". Second, in societies dominated by the conjugal family, it refers to kindred (an egocentric network of relatives that extends beyond the domestic group) who do not belong to the conjugal family.
These types refer to ideal or normative structures found in particular societies. Any society will exhibit some variation in the actual composition and conception of families. Much sociological, historical and anthropological research dedicates itself to the understanding of this variation, and of changes in the family form over time. Thus, some speak of the bourgeois family, a family structure arising out of 16th-century and 17th-century European households, in which the family centers on a marriage between a man and woman, with strictly-defined gender-roles. The man typically has responsibility for income and support, the woman for home and family matters.
Philosophers and psychiatrists like Deleuze, Guattari, Laing, Reich, explained that the patriarchal-family conceived in the West tradition (husband-wife-children isolated from the outside) serves the purpose of perpetuating a propertarian and authoritarian society. The child grows according to the Oedipal model typical of capitalist societies and he becomes in turn owner of submissive children and protector of the woman.
According to the analysis of Michel Foucault, in the west:
According to the work of scholars Max Weber, Alan Macfarlane, Steven Ozment, Jack Goody and Peter Laslett, the huge transformation that led to modern marriage in Western democracies was "fueled by the religio-cultural value system provided by elements of Judaism, early Christianity, Roman Catholic canon law and the Protestant Reformation".
In contemporary Europe and the United States, people in academic, political and civil sectors have called attention to single-father-headed households, and families headed by same-sex couples, although academics point out that these forms exist in other societies. Also the term blended family or stepfamily describes families with mixed parents: one or both parents remarried, bringing children of the former family into the new family.
Social conservatives often express concern over a purported decay of the family and see this as a sign of the crumbling of contemporary society. They feel that the family structures of the past were superior to those today and believe that families were more stable and happier at a time when they did not have to contend with problems such as illegitimate children and divorce. Others dispute this theory, claiming “there is no golden age of the family gleaming at us in the far back historical past”.
A study performed by scientists from Iceland found that mating with a relative can significantly increase the number of children in a family. A lot of societies consider inbreeding unacceptable. Scientists warn that inbreeding may raise the chances of a child getting two copies of disease-causing recessive genes and in such a way it may lead to genetic disorders and higher infant mortality.
Scientists found that couples formed of relatives had more children and grandchildren than unrelated couples. The study revealed that when a husband and wife were third cousins, they had an average of 4.0 children and 9.2 grandchildren. If a woman was in relationship with her eight cousin, then the number of children declined, showing an average of 3,3 children and 7,3 grandchildren .
Many religions, e.g., Judaism, encourage their followers to procreate and have many children.