Will I have to shell out for my children for ever?

The empty nest used to be a thing of parents' nightmares. Now - for many of us - it seems like an impossible dream. No more empty fridge, full washing machine, sharing bathrooms or running a taxi service? Not a chance - not with one in four young people still living at home.

According to the Office for National Statistics in 2016, some 3.3 million 20-34-year-olds are still living with parents, a 618,000 leap since 1996. A fifth of 25-to-29-year-olds are stuck at home, and half of those aged 20 to 24 and one in 10 aged 30 to 34 are also in the same boat. Young men are particularly affected, with one in three aged between 20 to 34 at home, compared to one in five women.

The shift is partly driven by sky-high housing prices, rising inflation coupled with wage stagflation. But the cost of university is important too: in 2014, 24 per cent of UK university undergraduates opted to stay at home living with parents while studying, compared to 12 per cent in 1996.

But while they save money, we parents are still shelling out. A report last year by Aldermore, the specialist bank, found that one in five savers lives at home, at a cost to parents of close to ￡5,000 a year. And a third of parents who have adult children at home are putting retirement saving on hold to support their offspring, it says. Perhaps not surprisingly, one in three said the tensions were damaging relationships.

So should you continue to support your grown-up child while also easing them towards the edge of the nest? And should you set a deadline?

Jane Peters, a 47-year-old administrator, and husband Steve, 47, a designer from West Sussex, who have two children Harry, 19, and Olivia, 13, say teaching self-sufficiency is crucial.

"Harry has just gone to university to read geography," Jane says, "and we are happy to pay his rent for four years, and support him this term while he settles in. But from Christmas we expect him to have a part-time job to pay his own food bills."

Her tough-love attitude is not surprising. "When I was younger, my parents told me that if I was living at home I had to pay housekeeping. I didn't go to university so when I started work as a PA I had to contribute ￡100 a month, which was quite a lot in 1988. But I wasn't saving for the future - I worked to pay for my love of travel and used to head off for six months at a time."

Then during one period of work, Jane's car - an old 2CV - needed urgent work. But when she told her father it meant she wouldn't be able to pay rent, his response surprised her. "He told me I had to pay my rent regardless. I was very belligerent. I couldn't believe he was being so mean. I had to take a second job waitressing at Pizza Hut in the evenings and on some weekends to find the money to repair the car."

Another lesson came from her mother: "She remembers picking me up from a temp job and hearing me say that I was too tired to go to work the following week. 'Where are you going to live, then,' she asked me, 'if you haven't any money for rent?'"

The balance for parents is a tough one to strike, says Simon Bashorun, financial planning team leader at Investec Wealth & Investment. "The responsibility goes on the parent. Many are caught understandably between the desire to be kind and that of teaching them to stand on their own two feet."

But he cautions parents that being generous is not without its own pitfalls. "If you do hand over a lump sum, not only will your children's motivation be lessened, but you also lose control over that sum. You can hope they are sensible, but that's all." And that's true of any child who benefited from one of Gordon Brown's Baby Bonds or whose parents set up a Junior Isa too. "At 18, that money becomes theirs," he points out. "If you invested the maximum ￡4,128 every year with about five per cent interest, the lump sum at 18 would be about ￡105,000."

Little wonder then that Bashorun believes educating children throughout their lives - not just if they boomerang back at 21 - is key. "There is a big onus to teach children about value early on." He adds: "It is a very challenging situation for parents too, as they may be worried about their own retirement, the possibility of funding long-term care for their own parents, let alone their children's futures."

Rose St Louis, savings expert at Zurich UK, agrees that teaching children about money when they are young is probably the most important thing parents can do. She says: "It's never too early to begin saving, so encouraging your children from a young age will stand them in good stead. It's important for children to understand that just because you have money, it doesn't mean it needs to be spent all at once. Think about opening a savings account so they can watch their pocket money grow." She is also keen on teaching children how to budget. "Helping them to set aside a certain amount every month will not only give them a lesson in budgeting but also teaches them the value of the items they're buying."

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Also, make sure they understand financial language. St Louis says: "It can be difficult to cut through the financial jargon and make sense of what's best for managing your money - this can be a particular issue if your children are just starting out in the world of work. However, not understanding the meaning of words such as APR on a credit card or interest repayments on an overdraft can really impact their financial futures. There are a number of resources to help - from leaflets in your local bank to resources from charity Young Money, which runs My Money Week."

When Jane Peters did leave home to rent a house with a friend in Southampton after four years, her parents didn't just send her off with sound financial training and a new kettle. "Dad handed me an envelope containing a cheque for ￡3,500 - all the rent I had paid them while living at home which he had invested for me. It was amazing.It really taught me the value of working hard for what you want."

She adds: "I really want to pass on those values to my children, so when the time comes, if Harry lives at home, I'll be carrying on the family tradition of charging him rent and secretly saving it up for him."