I have a wife and child, and we all live with my parents in a largish 6-bedroom house. They are retired and I support them financially. While they bought this house before I entered the workforce, I now pay the mortgage on this house. A few years ago we did a total rebuild of the house, and it's now a great living experience - something that neither my parents nor myself could have individually made possible. In a few years, as their health declines and they need support, it's easier for everyone that they are right here. Right now, they help a lot with childcare.
My wife and I - we just bought a second house that is fully rented out. While that one does not breakeven with its mortgage, it does end up being affordable.
My wife's parents and their son (my wife's brother) also live together. He is a doctor and supports them.
When I mention this to my coworkers or friends, the initial reaction is almost never positive. I've never understood that perspective. I don't mention it any more.