How big was the house your grandmother lived in with 5 siblings? Less than 1500sqft

Houses are something like more than double the size they were just 40 years ago, and families are smaller.

Oh, it's definitely possible to raise a large family with small square footage. My grandparents raised my father in a 3 bedroom house that can't be more than 1500 square feet. And my dad has 6 siblings!

It does depend on what families are willing to put up with, though. I'm not sure many of my millenial peers want to raise 7 kids in a 1500 square foot house. It's important not to ask what's physically possible, but instead what's probable given societal expectations.

Yeah I think you can't ignore the last part about expectations. I think younger Generations are just less willing to compromise on lifestyle to have children. The social institutions that made it much more attractive are crumbling. One obvious one of the churches, and the other is local community. It's one thing to want to have kids when all of your friends are doing it and you live together and can raise them together. Many of these communities are going away

Last time I was shopping for houses 1500sqft homes were rarely more than $5k cheaper than equivalent 2000sqft houses.