I am fully aware of that and that is why I wrote it the way I did. As in, you are quoting just one part, leaving out the most important part of that sentence:
Back in the day some of that
This implies a time at which at least the mother (in-law) was probably a stay at home mom. Please take note of the word probably. Yes there are and always were exceptions. It's about likelihoods and how societal norms and such have shifted over time. In fact we should probably add "and/or grand parents". And while at it also making extra sure this isn't mis-understood as an absolute or a "current situation" statement: "or living very close by" vs. today where you're more likely to live further apart.