More than 3.3 million 20 to 34-year-olds were living with their parents last year in the UK following a surge of one quarter since 1996 , according to official figures.
The number of young adults who have not yet flown the nest has grown by 25%, or 669,000 people, since Office for National Statistics (ONS) records began 18 years ago - with higher hurdles to get on the housing ladder and the struggle to find a job having left many in the younger generation trapped in the home they grew up in.
Last year's 3.3 million figure is the highest total recorded by the ONS series , although the number of 20 to 34-year-olds in the country's population has remained largely the same over this time.
The increase in those young adults living at home has accelerated since the start of the economic downturn, the ONS said.
In 2008, around 2.7 million people in this age group were living in the family home, but by 2011 this had jumped to 3.0 million and by 2012 the total was sitting at just under 3.2 million.
The rate of young adults living at home varies across the UK from around 22% in London - which has a large influx of young people coming to the capital for education and work opportunities, to 36% in Northern Ireland - where the ONS said young adults tend to follow a more "traditional" pattern of moving out of the parental home later, cohabiting less and marrying earlier.
Across the UK, those most likely to be still living with their parents are aged in their early 20s. Last year, nearly half (49%) of 20 to 24-year-olds lived with their parents, compared with one in five (21%) of 25 to 29-year-olds. One in 12 (8%) 30 to 34-year-olds were living with their parents in 2013.
The 20 to 24-year-old age group has seen the "most noticeable" jump in people living with their parents in recent years, the ONS said. In 2008, just two-fifths (42%) of 20 to 24-year-olds were living in the family home.
The ONS report said this rise "may be due to the recent economic downturn" as research shows that the young unemployed are more likely to live in the parental home.
It quoted labour market figures showing that 13% of the economically active population aged between 18 and 24 years old was unemployed during April to June 2008, rising to 19% in April to June 2013.
The rise in young adults living with their parents also coincides with a sharp increase in house prices compared to the average income of someone trying to get their first foothold on the property ladder.
The ONS report said that in 1996, the average price paid by a first-time buyer for a property was 2.7 times their typical income. But first-time buyers now face having to pay a price for a home which equates to 4.4 times their income as they stretch out their borrowing further or turn to help from the "bank of mum and dad" to help them build a chunkier deposit.
Government schemes such as Help to Buy, which offers people with a 5% deposit a helping hand on or up the property ladder, have been credited with helping to prompt a resurgence in first-time buyer numbers in recent months.
The Council of Mortgage Lenders recently reported that first-time buyer numbers reached their strongest levels in six years last autumn.
But in its "market commentary" published on its website today, the CML also said that while mortgage rates for low deposit borrowers could improve further in the coming months as Help to Buy stimulates fresh competition, this type of lending will continue to only represent a "modest share" of lenders' overall business.
Lending to people with deposits of 5% or less has represented no more than 2% of total new mortgage lending over the past five years, it said.
National Housing Federation (NHF) chief executive David Orr said: " Moving out and setting up a home of your own is a normal rite of passage...
"Unless we build more of the right homes at the right prices in the right areas, adult children will be stuck in their childhood bedrooms and parents will be unable to move on with their lives."
NHF research carried out last August found that two-thirds (66%) of parents with an adult child living at home said their child simply could not afford to move out.