Final answer:
The term used by anthropologists for a socially sanctioned economic and sexual union legitimizing children's position in society is marriage. Marriage encompasses various forms, but primarily is a socially recognized partnership that creates an emotional and economic unit within a society. Its definition is adaptable and can differ by cultural perspectives and practices.
Step-by-step explanation:
A socially sanctioned economic and sexual union that legitimizes the position of children within a society is more commonly known to anthropologists by the term marriage. Marriage is the formation of a socially recognized union that can be between a man and a woman, any two adults, or involve multiple spouses as seen in polygamous societies. It provides a formal structure for raising and nurturing offspring, forms emotional connections, and creates an economic unit within society.
While the concept of marriage can include various forms such as monogamy and polygamy, with monogamy being well adapted to postindustrial societies, changes are evident in contemporary Western societies. For example, in Iceland, a significant number of children are born to unmarried, committed couples supported by national policies, reflecting a more fluid understanding of family structures today. This trend illustrates the adaptability of social institutions and the potential evolution of the concept of marriage.
In practicing cultural relativism, we recognize that different cultures might not require a legal union for a marriage, and sexual orientation in the union can vary. Nonetheless, marriage is an institution that is nearly universal across cultures, facilitating not only the rearing of children but also the creation of alliances and social networks that can provide political and economic benefits.