It used to be the norm having several generations in one household. We’re moving backwards.
No, we're going back to sensible life styles, where the kids work their adult jobs for a number of years while saving money by living at home. That way, they'll have a 20% downpayment for the house they want to buy so they aren't enticed to do a no money down paperless sub-prime mortgage. That doesn't sound backwards, that sounds like progress to me.
The big difference is that back then, the oldest people in the house didn’t have the highest standard of living at the expense of the younger workers.