I grew up in a large family, and have slightly smaller accomodations for a family half the size. Not luxurious by any means; my home was probably built at the same time as the home I grew up in. The most noticeable difference between growing up then and living here now is the much smaller number of children; they are importing kids to keep the schools full.
A newer house saves a lot in utility bills. I know more people with large families now than I did growing up, and not just immigrants. In our subdivision, we and a Ukrainian Evangelical family both have ten children. We have a 2,400 sq.ft. house, and they bought two smaller houses side-by-side for the parents, children, and grandparents.
One of my friends from Mexico is one of 14 children, but only 4 are still alive, and she’s only in her 50s. She has only 2 American-born grandchildren.