The Sociology of Family is the study of the different types of families. It investigates how a person enters each and how this can affect society.
A family is defined as a group of two or more people who are related -- and consider themselves as such -- by blood, marriage or adoption.
When studying families, sociologists like to look at demographics, social class, ideology, domain, and interaction. They research these areas to learn why certain beliefs and/or lifestyles, for instance, are more prevalent in certain areas (or societies) over others.