Assyrian families were generally monogamous, with the home being core to the family experience. In a city such as Ashur which archaeologists and historians have extensively explored, certain patterns in Assyrian family life emerge.
What we see and do not see.
There are some things we see and some things we do not see. It was customary for people to be buried under their home, so we have domestic and skeletal remains that narrate a story of a single family — generation after generation — living in the same home and also being buried underneath it. However, usually, the home passed to the eldest son. So we actually know much less about the family stories of the other children who would have to move out when they were married. In many cases, the family stories of the children who moved out are altogether lost to us — this speaks to the vast, growing expansiveness of the Assyrian Empire. Nonetheless, we see that houses in the traditional Assyrian heartland were often smaller. Families who established themselves in the further provinces of the empire were able to expand their fortunes and these provincial households were, on average, of an entirely larger scale.
The nuclear family.
A typical home contained a husband and wife as well as their children, and often the husband's mother as well. Families were typically monogamous, except for the monarch and his consorts, although female slaves were often used sexually by male members of the family. But legal children – those who qualified as heirs, whether boys taking inheritance or girls receiving dowry – had to be the offspring of the legally recognized marriage between the husband and wife. Both mother and father were legally significant for defining the core of the family.
An Assyrian man would usually get married after his father passed away because marriage customarily happened only after he had received his inheritance. This meant the eldest son might already be in his late twenties or early thirties when he was married. Assyrian women were typically married around thirteen or fourteen years old — when they were still children themselves, really — as this was the youngest possible age that they could be physically expected to survive pregnancy and childbirth. Although men received their inheritance when their father died and then married, women received their inheritance — in the form of dowry — when they married and entered their husband's household. (If the couple divorced, she kept her dowry.)
Men and women married at very different points in their lives. A man married at an age to maximize his economic potential, while a woman was married at an age to maximize her childbearing years with her husband. When her husband died, she was substantially younger and often had many years ahead as a widow. Her male children would receive their inheritance and begin to marry. She would live out her life in the house, which now belonged to her eldest son, and the home would soon enough become full again with a daughter-in-law and grandchildren. Any other children of hers would also live in the home until they married and moved. Sometimes, brothers might agree to not divide up their inheritance and instead live in the house together. In this case, we see the house was adapted to accommodate multiple families cohabiting. The younger brothers might later take their share of the inheritance and move out to establish their own independent household.
Slaves of the family.
We see that in addition to the legally monogamous nuclear family in control of the household, Assyrians often owned slaves who belonged to the household as well. The wealthiest families may have dozens of slaves as part of their home.
We see that the household slaves and the nuclear family had more than just a binary relationship. Not only did a slave belong to a family — so did the slave's children as well, in perpetuity, with the effect that slaves were born into a family. Also, female slaves were the sexual property of the family, which meant that many slaves were related not just to one another but may be half-siblings, cousins, or children of members of the nuclear family. Children of a man with his slave were legally outside his officially recognized and legally monogamous nuclear family and thus also, of course, ineligible for inheritance.
The closeness of the household's owners and the household's slaves may explain why Assyrian families did not sell their slaves unless they really had a very strong reason. In the most extreme grey areas, we even see adoptions of slave children into the nuclear family. However, there was nonetheless a slave trade, especially to sell prisoners of war, and exotic foreign slaves from outside the Assyrian Empire were prized — Anatolians were particularly sought-after, for unknown reasons.
The royal household.
The Assyrian royal family had some remarkable differences with the normal family,
Scale — the royal family was much larger in scale in terms of the palace, servants, and all other measures of the household.
Official non-monogamy — totally unlike a regular family, only the king could practice non-monogamy and see all his heirs recognized as legitimate.
Burial — when the capital moved from Ashur, the king was not buried under his palace with the rest of his family, but instead he was buried under the old palace in Ashur.
The continuation of the royal dynasty was of paramount importance. There could be no risk taken that offspring would not be produced. All children who the king begot with his consorts — not just his one legal wife — were also legally recognized as his heirs and thus eligible for kingship. The queen was, ironically, in some ways less important than regular wives. Very often, we do not even know who was a certain king's mother — the only thing that was legally significant is the link to the king before him, and so forth.