The meals are hot, the fridge is always full and the rent is free. So is it any surprise that more twenty- and thirtysomethings in Britain are living at home with their parents than at any time in the past 20 years?

The Office for National Statistics says many young adults in their mid-20s and early 30s, and especially men, are increasingly postponing the transition to adulthood.

One in three "adult-kids" who have not left the parental nest say they are still living at home because they cannot afford to get a toehold on the property ladder by buying or renting. But others, who have been dubbed kippers – kids in parents' pockets – are, say the demographers, staying through choice.

In the past, British children have tended to leave home earlier than their European cousins but the latest ONS figures, published today, show that 25% of men aged 25 to 29 now live with their parents. This is almost double the proportion of women in their late 20s (13%) who still live at home.

The official statistics also show that, for more than 10% of men who have reached their early 30s, home is still with the parents; this compares with 5% for women of a similar age.

The statisticians show also that among those who have left the family nest there has been a shift away from their moving in with a partner to living alone or sharing with others.

The demographers say the reasons behind the change vary according to social class, and that the last 20 years since 1988 have seen changes in the opportunities and constraints faced by young people in their transition to independent living.

On the one hand, the massive expansion in higher education has seen the number of undergraduate students triple since 1970, from 414,000 to 1.27 million. On the other hand, the collapse of the youth labour market during the 1980s has been followed by a continuation of high unemployment rates despite periods of relative economic buoyancy.

"The recent recession has been accompanied by a sharp increase in unemployment rates among young adults," says an article by Ann Berrington, Julie Stone and Jane Falkingham of Southampton University, published in the latest edition of Population Trends.

The authors say that recent graduates, especially men, are increasingly returning to live with their parents after graduating. The demographers call this group the "boomerang children". Their numbers are being swelled by the increasing levels of student debt they have accumulated by the time they finish their studies. And those with few educational qualifications are increasingly facing long periods of unemployment and can't afford to leave home.

The lack of jobs is being compounded by changes in the housing market. Even those in work cannot afford to move out of the family home as first-time buyers now face house prices that are, on average, five times average incomes, compared with a multiple of three times 20 years ago.

But they add that these factors only partly explain why people are also postponing forming families and perhaps marriage.

"It is also a reflection of the changing roles of men and women and changing expectations of normative ages for partnership and family formation," say the authors. "It is unclear the extent to which remaining in (or returning to) the parental home is an outcome of choice rather than constraint for these 'emerging adults'."

The authors do say that their results suggest that the transition to residential independence among young adults is becoming increasingly protracted and reversible for all age groups.

Even when they do finally leave the nest, the twenty- and thirtysomethings are still postponing the moment of settling down with a significant other. This is borne out by the fact that the average age for forming a stable partnership and having children is rising among more affluent young adults.

The report notes: "Over the past 20 years there has been a move away from living in a new family (especially a couple) and a move towards living outside a family (either alone or sharing with others).

"Moreover, although a minority are living outside a family at a given point in time, many more are likely to have experienced this type of living arrangement at some point during young adulthood."

These changes mean that "many more advantaged young adults appear not ready to settle down during their 20s and are likely to return to the parental home before setting off once more". The social scientists add: "For this latter group of 'emergent adults', living with a parent may often be the preferred option until partnership or family formation."

The study also shows up strong regional variations around Britain in the pattern of adult offspring still living with their parents. The proportion of "kippers" is highest in Northern Ireland, the West Midlands, outer London and parts of the north-east beyond Tyneside and Wearside.

The proportion of those living at home with their parents is lowest in inner London, south Yorkshire and west Yorkshire, partly because of the greater number of colleges in the region.

Stay at home kids

• Young adults in their mid-20s and early 30s are more likely to be living with their parents in 2008 than in 1998.

• This is more likely to happen in Belfast, Glasgow, Birmingham and outer London.

• When they do eventually leave home, young adults are more likely to be living alone or sharing with others than "settling down" with a partner.

• Young men who are unemployed are increasingly likely to be living at home in their early 20s.

• More college graduates – boomerang kids – are returning home to live with their parents in their early 20s.

• Twice as many men as women are living at home with their parents.