I'm not sure about that. Parents siphoning their children's (or children's spouses') "excess" income as a substitute for emergency and retirement savings seems pretty destructive. Rather than a self-perpetuating cycle of wealth transfer forward (i.e. paying for college), children start out less advantaged and, once they have earning power later in life, are expected to contribute it backwards. Of course, what you are expected to "reciprocate" here is not usually free housing as an adult, but your upbringing in general.

I'm very grateful that my parents have been fiscally responsible, and have taught me to do the same. While I will of course take care of them as medical situations arise (as they're currently doing with their parents), I very much appreciate that we're not in a tradition of tithing to our elders like so many other families seem to be. I can only hope that my eventual spouse would feel the same way. I certainly would not expect it from my children. But if my parents demanded it, then I'd have no choice but to demand it.