The Pew Research Center defines a multigenerational household as one with grandchildren and grandparents, or with two or more adult generations. Technically, every home with parents and children is multigenerational, but this is a standard arrangement which is not covered by the term. Historically speaking, all households are multigenerational, with family members not living together being a more modern phenomenon. It was common for families to inherit homes from either parents or grandparents, mainly when life expectancy was lower. Nowadays, this is less common, with each generation generally desiring their own homes, particularly in the western world.
In eastern cultures, it is far more common to find multigenerational homes, although this has begun to change in recent years, particularly with the development of multi-storey housing, which necessitates smaller homes. In many Asian countries, houses were built multi-storey with younger generations living on the upper floors, and older generations living on the lower, so they have fewer stairs to climb. Of course, wealthier families would typically prefer to have homes that are single-storey and spread out over a more substantial amount of land, but this was not possible for everyone.
Multigenerational homes may be making a comeback in many countries in the west; sometimes this can be desirable, as it is likely that living with the family will lead to a higher quality of life rather than living in state-sponsored care homes. There are difficulties with multigenerational homes which aren’t present in more modern households. In particular, the different styles of raising children may become an issue, as well as the division of financial responsibility. These are things that are better to discuss in advance for anyone planning on living in a multigenerational home.