A growing number of older people, many living alone, has also increased demand for property. While previous generations found it easy to raise a mortgage, today's under-thirties have to live with their parents or rent.
Professor Tinker said her research was supported by General Household Survey statistics.
The survey, which is carried out regularly, is aimed at discovering facts about the way we live that are not revealed through traditional records and censuses.
Between 1993 and 2000, the proportion of under-25s owning their own property fell from 21 per cent to 19 per cent.
The number of men aged 25 to 29 living with their parents rose from 18 per cent in 1978 to 23 per cent in 1998.
Even more revealingly, the 25 to 35-year-olds living without a companion or spouse rose from 2 per cent in 1973 to 12 per cent in 2000.
On a positive note, Professor Tinker said prospects had improved for those facing old age. 'Older people are in better health today,' she said. 'They are staying in work for longer or being wooed back to work.
'They may also contribute to society in unpaid work, such as childcare. Care of grandchildren is hugely important.'
Professor Tinker's research follows a report last month that showed debt among young people soaring, with some under-30s more than £30,000 in the red.