George Murdock (1949) - 4 Essential Functions of the Family:
reproduction - family is the main unit of reproduction for children, without this society would cease to exist.
education - the family is largely responsible for primary socialisation, the first and most important part of the socialisation process, without a shared culture there would not be a shared consensus about norms and values.
economic: the family is a unit of production, in the west today the family acts as a unit of consumption which is buying goods and services for the family, this makes an important contribution to society.
sexual: there are rules limiting or forbidding sexual relationships outside of marriage, this helps to stabilise the social system and prevent conflict.