Do you have kippers for breakfast? You’re probably wrinkling your nose right now, thinking no. But think again. A kipper is a ‘kid in parents’ pockets eroding retirement income’. In other words, it is an adult child living with their parents – often rent or bill free.

According to the 2006 Irish Census, 280,065 ‘children’, predominantly male, in their 20s and 65,693 in their 30s live with their parents. In the UK, a survey indicates that two-thirds of adult children living with their parents do so rent free.

Prof Sheila Greene, director of the Children’s Research Centre at Trinity College Dublin, says the centre’s annual lecture in 2007 was on this topic, termed ‘emerging adulthood’ by speaker US psychologist Jeffrey Arnett.

According to Arnett, there is now a period between adolescence and adulthood that he calls emerging adulthood.

“This is mainly driven by economic, social and educational factors: more people are spending a longer time getting qualifications and are dependent on their parents for longer. There is also a longer delay in taking on responsibilities traditionally associated with adulthood such as having children, buying houses and deciding on a career,” explains Greene.

She says that the affluence of middle-aged, middle-class people and smaller families means that parents can support their children for longer. The high price of property also means that children chose to live at home. Liberal attitudes of parents also help – in the past, if a person wanted a sex life in their 20s they’d have to leave home, she adds.

“Obviously, there are young people who are not cosseted in this way and whose parents can’t afford to keep them at home without charging rent or because they don’t have the room. It’s quite a middle-class phenomenon.”

Greene believes that, if a family has a situation where both sides are happy and contribute to each other’s wellbeing, it doesn’t have to be a problem.

“One could argue that it is a problem if a person of 30 has never had to manage a budget or stand on their own feet.”

However, she says, you can’t generalise. The person is not always terribly dependent and generally pathetic about coping for themselves. There are people who have a very workable way of living with their adult children as three adults rather than two adults and a big baby. If people are being exploited, however, it’s a different matter.

“If the parents are sick of it they should say so, tactfully or less tactfully. They shouldn’t feel they’re going to upset their offspring in that way. They should be able to say what they want; they’re entitled to say what they want. They’ve worked hard, they’ve got their house, and maybe they’re looking at retirement and want to do something different. I think they should be able to say it without worrying that they’re upsetting their grown-up child. People need to be treated as grown ups, not big babies, that’s the point.”

Taking longer to grow up is a widespread phenomenon and is not just down to soft-hearted parents, notes Greene. “It is quite a widespread phenomenon and there are understandable reasons why it has happened.” Everything is taking longer, she says. “Parents have to accept the pattern now is not the same as when they were younger.”