But the 'boomerang' generation has been driven back by skyrocketing house prices and rents, and a jobs market flooded with well-educated people competing for fewer well-paid posts.
The psychological ramifications are serious. German researchers, who analysed data on 20,000 young adults, found those who move back to the family home are at increased risk of depression.
That's certainly my experience in my clinics, where I've seen large numbers of men and women in their mid to late 20s — even well into their 30s — still ensconced in the family home and suffering.
They have lost the sense of self they found at university, and feel frustrated and angry at their inability to establish homes of their own as their parents did.
Independence — economic, social and residential — is a hallmark of adulthood. And while they understand things are different, especially after a global recession, it doesn't take away from their belief that life has stalled. This can trigger a regression to adolescent behaviours such as disregard for house rules, petulance and a sense of entitlement so they treat their home like a hotel.
Researchers at the London School of Economics, meanwhile, found the quality of life for Mum and Dad also deteriorates to the point where it's as bad as if one of them had developed a disability.
I've had people tell me how guilty they feel, because a part of them wants to be rid of their adult offspring. They are also saddened by their children's frustration.
So how can you minimise the disruption? I think tough love is the answer. There must be some very clear ground rules to stop the inner-teenager resurfacing and you subconsciously reverting to the kind of relationship you had with your child years ago.
Shift your mindset — this isn't a beloved child but a tenant and he or she must pay rent or at least contribute to household costs. Nothing in life is free — even in the bosom of the family.
And stop parenting. Don't pry into what they are doing and don't ask when they'll be back. Never do their washing or ironing. Never open their mail or go into their rooms (unless invited).
If there is an abundance of mouldy socks posing a biological health hazard, that's their problem not yours.
Limit family meals to once a week, and in general they should be responsible for buying their own food. Clear out a cupboard in the kitchen for them and allocate a shelf in the fridge.
Treating your child like a lodger might sound grim, but in the long term it affords them the distance they need to maintain their independence — and the boundaries you need to keep your sanity.
