Why are nuclear families increasing?

Parsons, a functionalists gave the reasoning behind this. He came up with the functional fit thesis, which states that different family types are better suited for different stages of society.

Parsons says that the nuclear family was dominant in industrial society for 2 reasons

1) it is geographically mobile

Industrial society requires a workforce that can move about in search of new jobs when they arise around the country, and the nuclear family is therefore the perfect size to move about regularly in search of work

2) it is socially mobile

In industrial society, meritocratic values are dominant, this means that status is achieved rather than ascribed, so hard work = high status in a nutshell. Therefore, you can have a family whereby the father is a plumber and the son is a top lawyer, and if the father and son lived together there would be conflict of status. Therefore the nuclear family allows the next generation to not live with their parents during adulthood, which means that conflict of status can be avoided.