When David Chalke's three children left school they were - ever so gently - pushed out of the family home. The children spent a year or two in university halls of residence, then rented houses near the uni - bankrolled by Chalke while they were still studying.

"We bribed them out of the house," laughs Chalke, a social analyst who compiles the annual AustraliaSCAN survey. But he notes that his baby boomer contemporaries increasingly are not getting rid of their adult children, even with bribes.

Data from the 2006 census show 38 per cent of 20- to 29-year-olds still live at home, compared with 30 per cent in 2001 and 21 per cent in 1976.

The trend has spawned some clever labels, including helicopter kids (hovering around the family home), boomerang kids (leaving then coming back) and kippers (kids in parents' pockets eroding retirement savings).

It's a predominantly middle-class phenomenon, according to demographer and author Bernard Salt, because higher-income baby boomers tend to have big houses and the cash flow to support adult children, their live-in lovers and several cars.

"Up to 24, it's probably fair enough these days because of the HECS debts," says Salt, who has two children, aged 18 and 21, living at home while they study. "Really, the education phase has moved beyond high school. But after 25, it's hard to argue there's a legitimate reason to be at home."

His analysis of census data shows 18 per cent of 25- to 29-year-olds haven't fled the nest - and in some affluent outer suburbs of Melbourne and Sydney, it is more than 50 per cent.

Plenty of reasons are offered: soaring house prices in Sydney and Melbourne have locked some first home buyers out of the market, while tight rental markets make leasing difficult.

Half of all school-leavers go on to some form of tertiary study, which usually delays getting married, having children and buying a house. Hence, the term "adultescents".

Dominic Thurbon, the managing director of gen Y consultancy The Centre for Skills Development, has another theory: "Gen Y like their parents. They've been parented from positions of friendship, so it has been a more collegial, collaborative home environment." As for the baby boomers, Salt says their official line is they want their kids to move on but, unofficially, they need the ego-boost of being at the centre of things. Sure, there's more washing, cooking and cleaning - not to mention the cash sucked up - but Salt says it's part of the boomer culture to be in control rather than obsolete.

Whatever the reasons, the arrangement sounds like a win-win scenario for parents and children.

But there is a dark side.

Despite the average gen Y having the same level of disposable income as a one-child family, according to Thurbon, there is no knowledge of the cost of living and the level of affluence required to sustain a lifestyle.

Thurbon says: "It's feeding a general problem of financial illiteracy amongst young people, where they have the income element without the responsibility elements."

Chalke says: "If you get to your 30s and you haven't acquired the mindset for financial skills such as budgeting, it gets a heck of a lot more difficult. If you've had 10 years spending your entire disposable income on entertainment, fashion and travel, you won't have learnt how to cope with a changing world or how to do without the $4 latte on the way to the office."

It's a problem the baby boomers are gradually waking up to, according to Penelope Joye, an adviser with the Shadforth Financial Group. "Many of my clients have financed themselves without the benefit of wealthy parents and did it pretty tough, so they've been happy to spoil their kids," she says.

"In retrospect, some clients now feel they did not do their children any favours, as they feel the kids don't understand the costs associated with their comfortable lifestyles."

The global financial crisis has shaken some parents into action. Their super fund, share portfolio and house are worth a lot less than a year ago, so they are watching their cash flow and feeling less benevolent towards adult children.

"Clients have implemented strategies such as barring calls to mobiles from the home phone, disconnecting Foxtel and not stocking the fridge," Joye says.

But the real, long-term benefit will come from encouraging young people to take responsibility for their finances, Joye believes. Some clients bring children as young as 15 to Joye's seminars on budgeting, regular savings plans and superannuation.

She also believes in charging board. "This encourages responsibility and discipline and will stand them in good stead when they are on their own."

Director of Haywood Financial Management, Scott Haywood, says many of his baby boomer clients charge board of at least $50 a week. If the parents see their offspring blowing their salary at the pub every week, they will increase the board.

Some invest the board on the child's behalf or waive the payment if the equivalent amount is invested directly by the child. Another of Haywood's clients has gifted the board paid for two years back to a daughter, who is moving out and needs to buy whitegoods and furniture.

Financial planner Dickson Bonacci's principal adviser, Sylvia Dickson, says her clients often mention the cost of their adult children living at home. This may be direct costs, such as increased food and utility bills, or indirect costs, such as being unable to downsize.

"They will refer to it as short-term but in my experience it very often extends beyond this timeframe," she says.

"Although they are good-humoured about it, there is usually some impact on their lifestyle and their own plans are often deferred or derailed by children still living at home."

The result, she believes, is a generation of young adults with unrealistic expectations.

"They want to exceed their parents' achievements but in a timeframe that is truncated by a reduced working life - settling into careers later due to higher education, gap years, employment changes, travel - deferring events such as home ownership, children and education expenses until their 30s and 40s and then hoping to retire at an earlier age."

As with Joye, Dickson says the key to teaching children financial independence is education - especially about the benefits of early accumulation of superannuation.

"For many, the current economic downturn will be their first experience of an unfavourable environment. Most have enjoyed full employment and an extended period of prosperity for their parents through rising property prices and sharemarkets."

You might expect the economic downturn would lead to more kids being flung from the nest earlier. Quite the opposite, the experts say.

The baby boomers are aware their kids face a much tougher jobs market.

"This will further reinforce the 'Let's stay at home' model," Chalke predicts, adding a tide of young expats will return after losing their jobs in New York and London. But he also expects the crisis to have a positive effect. " One of the good things . . . is that it may lead to a simpler, more disciplined, less self-indulgent lifestyle for baby boomers and their kids."

Salt agrees.

"It's time to grow up, you're twenty-bloody-nine," he says.

Mum knows best

Last year, Jane Taylor suggested to her eldest son, Mitchell, then 20, that he might pay $50 a week board. He was working full-time and she planned to put aside the board to give back to him at a later date.

He decided if he was paying board, he may as well move out - and he's now paying $250 to rent a small flat. "Silly boy," laughs Jane.

Jane, 52, and her husband Chris, 54, have two other sons still living in the couple's five-bedroom home on Sydney's North Shore.

One son, aged 17, is still at school, while their 19-year-old, Cameron, is working full-time at a financial advice company after deferring a university course halfway through the academic year.

They're happy not to charge Cameron board, although since he started work he is expected to pay for the petrol, registration and insurance on his car.

"I don't feel at this stage any need to charge rent," says Jane, noting Cameron is not a spendthrift and uses all his spare cash to build a share portfolio. She says he is also very helpful - mowing the lawn, gardening, fixing the computer and driving his younger brother around.

"Why show them the door?" she says. "The four of us live in harmony and if you can help [your children], that's a good thing."

The little household that could

Comedian Denise Scott devotes the final chapter of her book, All That Happened At Number 26, to the joys and travails of living with her two adult children.

She and her partner, John Lane, share their home in Melbourne's north with Jordie, 24 - a singer-songwriter - and Bonnie, 22 - an installation artist. Neither pays board; in fact, both sometimes need to borrow money from their parents to finance their creative pursuits.

"I really respect my kids' attempts to become artists and I'm happy to support them financially," Scott says. "And I've always had the belief that if I've got money and someone else hasn't, I should share it."

The family gets on well, although the house has only one living space - and Denise and Jordie both work from home.

Denise's main gripe is housework. The children do their own washing and will cook if she hasn't done so but that's it - despite Denise papering the house with notes about unpacking the dishwasher and clearing the bench.

Money talks

* Encourage your adult children to take their finances seriously. A seminar covering topics such as budgeting, regular savings plans, superannuation and compound interest may help.

* Charge board and/or a contribution towards household bills. Some parents "gift" the amount collected back when the child is buying a house or a car.

Consider "deals" such as matching a saving of $1000, for example, with an equal contribution into the child's superannuation fund.

* Encourage your child to see a financial planner to discuss strategies to make the best use of money, including the Government co-contribution for super, first home owner's grant and nominating a growth option for their super.

* Explain the benefits of contributing early to superannuation.

Source: Financial planners Sylvia Dickson, Scott Haywood and Penelope Joye.