Sociologist George Murdock defines the family as a social group with common residence, economic cooperation, and reproduction, highlighting various family structures including nuclear, extended, single-parent, and reconstituted families. The document also discusses the influence of industrialization, divorce, and social class on family dynamics, noting that lower-class families are more likely to be matrifocal or single-parent, while higher-class families tend to be nuclear. Additionally, state benefits for single parents have led to an increase in single-parent families, reflecting changes in societal norms regarding marriage and support.