In the context of human society, a family (from Latin: familia) is a group of people affiliated either by consanguinity (by recognized birth), affinity (by marriage or any other relation ship like siblings families etc..), or co-residence (as implied by the etymology of the English word "family") or some combination of these. Members of the immediate family includes spouses, parents, brothers, sisters, sons and/or daughters. Members of the extended family may include grandparents, aunts, uncles, cousins, nephews, nieces, and/or siblings-in-law. Sometimes these are also considered members of the immediate family, depending on an individual's specific relationship. In most societies, the family is the principal institution for the socialization of children. As the basic unit for raising children, anthropologists generally classify most family organization as matrifocal (a mother and her children); conjugal (a husband, his wife, and children, also called the nuclear family); avuncular (for example, a grandparent, a brother, his sister, and her children); or extended (parents and children co-reside with other members of one parent's family). Sexual relations among the members are regulated by rules concerning incest such as the incest taboo. The word "family" can be used metaphorically to create more inclusive categories such as community, nationhood, global village and humanism. The field of genealogy aims to trace family lineages through history. Family is also an important economic unit studied in family economics.