Boomerang generation - quarter of couples have an adult child living with them as 'moving back in with mammy' is the only option
Adult children are being forced to stay longer in the family home, prompting a collapse in the numbers of older people who are downsizing.
"Moving back in with mammy" has become the only option for many young adults due to surging rents and a chronic shortage of properties to buy.
These young adults are often called the boomerang generation, because they bounce back to their parents' houses after leaving home for a while, or never leave the nest.
It has now emerged that a quarter of married couples currently have adult children living with them.
Recent suggestions from economists that "empty nesters" should be incentivised to move out of their homes to smaller properties drew a furious response from older people.
The lack of houses to buy and rising prices of properties and surging rents are prompting more young adults to remain in the family home, the new research from estate agency Savills has found.
It calculated that the proportion of house sales resulting from downsizing has collapsed from 13.4pc in 2014 to just 5.3pc last year.
This is despite the fact that an average gain of around €350,000 can be made by older people selling up the family home and trading down to a smaller property, according to director of research at Savills John McCartney.
Rising property prices and a shortage of suitable properties to downsize to are cited as reasons for older people declining to sell up and move to a smaller home when they need less space. Older people are also reluctant to leave their community.
"Adult children are taking longer to fly the nest due to high house prices and rents," Dr McCartney said.
He said Census figures released last week showed the number of couples living with children who were over the age of 20 had gone up. The figures show that 132,500 married couples now live with an adult over the age of 20. This represents 25pc of married couples.
This is despite an overall decline of 87,282 in the number of twentysomethings since 2011.
And the proportion of older people living alone has fallen as their grown-up children stay longer at home.
"This trend is particularly evident in less affluent areas where family money may not be available to help young adults on to the housing ladder," Dr McCartney said.
Rising prices mean that many older people who are living alone have decided to hold out before considering trading down in the hope of even bigger capital gains. Dr McCartney said another major factor was the fact that the quality of trade-down stock had not been sufficiently attractive to entice those looking to trade down out of their existing homes.