I'm a father of 7 children. I'm the youngest of 5 siblings and my wife is the youngest of 6 siblings. Both of our mothers had college degrees and jobs and chose to stay at home with the children, and neither of our fathers had anything other than middle-class incomes.

My wife has also chosen to be a homemaker, and I watch in awe at how much she gets done. She creates a space where the "slack" you mention can happen--that is where we can afford to be generous with our time. I don't see it as a financial income thing, but more of a lifestyle thing (arguably the same thing).

We've lived in both Sweden and in America, and we've modeled our family life by looking at the older families in both cultures that seem to be thriving--and building in this slack, building in someone who can simply _care_ for the others and be cared for in return has been amazing.