My wife and I are "grown ups" in the sense that we both are done with grad school, have professional jobs, and have a kid. Yet, my mom lives with us during the week and we spend nearly every weekend at my parents' house in D.C. Not because they need our support, but because we need theirs'. This is a living situation that wouldn't be unfamiliar to my grandparents back in Bangladesh, where the expectation, back then, was that a young couple would move back into the husband's parents' home after marriage. It's novel relative to what I encountered growing up (in the U.S.), but it's not "new."
Various studies have shown that Millenials are closer to their parents than any generation in recent memory. They are not only likely to live with them after graduating college, but turn to them regularly for career advice, take them on job interviews for support. It's the opposite of the rebellious streak that characterized the baby boomers.