Fledglings have no option but to stay in the nest
Time was when people in their 20s could not wait to leave their parents' home and strike out on their own.
The comforts of home are many, with mammy making dinner and dad always around to help with a lift. But living with the parents can be suffocating.
Bringing home a boyfriend or girlfriend is a tad awkward when your parents are at home. And no matter how old you are, your parents will still want to know what time you are due back when you go out.
That is why a strike for freedom by renting somewhere or buying is the standard move for those in their 20s and 30s.
But in a reflection of the dysfunctional housing and rental market in this country, it has now emerged that huge numbers of young adults are staying put in the home of mum and dad.
For many older people, that is a less than ideal situation.
A striking one-in-four married couples now has a young adult living with them, according to figures extracted from Census 2016 by Savills' research director John McCartney. And the overall number of millennials living with their parents is up despite a contraction by 290,000 in those in the 20 to 34 years age bracket since 2008.
The record rises in rents and surging house prices, and a chronic shortage of properties to buy, mean that young people are unable to set up home on their own.
This partly explains why we see repeated reports about millennials having so little sex, and partly explains why birth rates are falling.
Market research people call young adults who live with their parents the boomerang generation.
Rather than flying off to create an empty nest, the fledglings stay at home.
There was a furious backlash from older people when economists suggested a while ago that "empty nesters" should sell up, as their downsizing would free up homes for families.
That debate has been rendered moot by the information that so many married couples have an adult living with them. Anyway, older people are content to sit tight and resist any move to downsize when property values are surging by 10pc a year.
By waiting another year, their €400,000 home will be worth an extra €40,000. So why sell up?
And there are few homes suitable for older people to move to.
For their sons and daughters, our messed-up housing market leaves them trapped.
Rents rising at a rate of 15pc a year mean it is too expensive to move into rented accommodation. And never mind the Government's Help-to-Buy scheme - there are still not enough new homes being built.
All this means that for many, the nest will remain a crowded place for a while yet.