In ancient Mesopotamia the family was the basic unit of society that was governed by specific patriarchal rules. Monogamy was the rule, even though the nobility could have concubines. The purchase of wives from their fathers was common, but the practice became less common after 3000 BC.
The woman was allowed to do anything and go anywhere, including conducting business, as long as her husband permitted it, or she was a widow. In the case of a divorce, both partners had to pay a fine. Nonetheless the husband was at an advantage: A childless wife was could be divorced easily, and a wife who left her husband faced severe penalties. Conceiving children was the main purpose of marriage. As it is still the case in many societies today, boys were preferred.
Children had to respect their parents, as contempt of one's father or mother was seen as a grave sin. Family unity was seen as paramount, which is reflected in the way the gods were believed to be related and respect each other. Selling children was only done in dire financial difficulties, and was often seen as a bad omen.
The extended family included the household slaves as well as the clan. Family and clan were seen as systems of mutual support, both financially and morally. The members of a family were seen as responsible for each other before the gods.