If you think about it, the nuclear family is a necessity of class society. Whenever human beings were first able to produce enough agriculture such that there was excess, there needed to be a fundamental re-configuration of traditional familial structures. This was needed so that accumulation of excess agricultural production was possible.
Traditionally, families were arranged communally. Whole communities were responsible for raising children, thus the phrase “it takes a village.” Entire communities did the sowing, maintaining, and harvesting of food from the land. The land was communally owned.
Due to the ingenuity and ability of human beings to come together in groups and rationally decide the best way to produce what was necessary for life, eventually, excess food was produced above and beyond what was required to keep everyone in the community alive. In these early societies women did not have as much opportunity to be involved in agricultural work because infant formula did not exist and biological circumstances dictated that they were in charge of child rearing. As humans became better and better at producing excess food, it was men who happened to be closest to this newly possible resource and therefore were in an advantaged position to take control of it.
Slowly, over time, excess began to accumulate, it was clear to the men who were in control of it that there was power in controlling it. Motivated by power, it became obvious that maintaining control of the excess would require an entirely different system to facilitate their desires for power.
In a communal family system where the land and familial responsibilities are shared equally with everyone, taking control of accumulated excess food production was impossible. Once you take control of the excess who do you spend it on? Where would the accumulated excess go once you died? Where would you get it from, the very land in which everyone owns together? Such a communal system was not conducive to seizing control of accumulated excess food production, something new was needed.
Thus the concept of the nuclear family and private property were born. The nuclear family was a necessary development of class society due to the need to be able to seize control of excess accumulated food that was produced. The nuclear family arose not because it is “natural” “holy” or the right way to order society but rather because it was needed as an economic unit to maintain control of excess, of wealth. Now a man could seize control of wealth and be sure that it would not be redistributed to society as a whole when they spent it and when they passed away. Instead of the wealth going to everyone in the community upon the passing of the man who seized control, it would only be able to go to members of the man’s nuclear family.
Along the same vein, it was now important that the man knew who his offspring were whereas in the past it was not important since everything was shared with everyone anyways. The need for men to possess women arose so that it was certain who were members of the nuclear family acting as an economic unit he was a part of. Along comes patriarchy and subordination of women as yet another necessary mechanism for maintaining control of wealth.
Finally, land would need to be taken possession of. Otherwise how would the man be able to claim that whatever excess was produced was indeed his? From communal land only communal goods can be produced, that needed to change.
The advent of excess agricultural production required a paradigm shift in the way society was ordered so that the possession of excess agricultural production, of wealth, was possible. This required the existence of a nuclear family, private property and a sexist patriarchal system of oppression of women.