It’s the moment almost all parents wait for – graduation cap in hand, the chicks finally leave the nest. Spread your wings and fly little birdies, mom and dad think to themselves. It’s just a pity that lately the peace and quiet doesn’t seem to last long.

Initially it looked like a blip that would pass, but multigenerational households are here to stay, at least for the near future. In fact, one in four Americans now have such a setup at home. Global property prices have ballooned and many a qualified and employed millennial cannot come up with a deposit for a roof in the central business district without the help of The Bank of Mom and Dad.

More young adults are moving back into their childhood rooms, because it’s the only ‘rental’ they can afford. In hubs like London, it’s not odd to see ‘To Let’ signs hanging in front of once thriving nightspots like The Magician Rooftop Bar. The youngsters have gone and so has their business.

A few years ago, tech entrepreneurs thought they’d create affordable housing only for the poor, by using 3D printing or muck-based bricks; but now it’s becoming increasingly clear that the middle class is a booming market for instant homes.

Australian building contractor Mike Roberts says that he’s never been as busy in his life. “The parents don’t mind that the children come back home, but they don’t want them in the house. They want separate cottages or detached flats in the back yard,” he chuckled. “I think it’s just to keep everyone’s sanity in check, mate!”