The break-up of the extended family is being held back by rising house prices according to a new report.
More than half of Britain's young adults live with their parents and the proportion is rising as 18-24 year olds, many with student debt, struggle to afford housing.
The rise in house prices above levels that most young people can afford has created a new generation that is being nicknamed the "homebounders".
The homebounder does not willingly remain in the family home, but is living there only because it is too expensive to move out.
The new term reflects an "innate desire to move out yet an inability to do anything about it", according to Datamonitor, the research group which wrote the report, Young Adults' Living Arrangements.
Daniel Bone, the report's author said: "For the vast majority of young adults, living in the parental home does not fully reflect their aspirations and desires for independence."
Housing costs, student debt and cuts in benefits were the three main obstacles to leaving the family home, he said, a situation which is similar throughout western Europe. There the average proportion of 18-24 year olds living at home is 65.3% - a total of 24.9 million.
The number of homebounders has increased from 55 per cent in 1997 to 57 per cent in 2002. The average house price is £118,500, according to Nationwide, although this figure is considerably higher in the South.
The report also identifies a growing phenomenon it terms "boomeranging", where young people who have left home return to their family home.
In Italy and Spain there is a long tradition of young adults living at home at least until they are married and well over 90% now do so.
The figures for France, Germany and the Netherlands were similar to the UK; the exception was Sweden where the proportion fell from 48% in 1997 to 46% last year.
Cohabiting with partners is the most popular alternative to living with parents, chosen by 4.3m young adults across Europe, compared with 1.62m house sharing and 3.3m living alone.