Today children stay at home well into adulthood, and most parents can tell you that with as much authority as I can. They stay at home when they go to university and they stay at home when they get a job, and soon I expect that they'll be staying at home when they marry.

And when they do move out they return to live at home when flats or relationships are dissolved, between jobs or to save money for an overseas trip or a house deposit.

One of my three daughters is about to return home for that stated purpose, to save for an overseas trip, and in my column in The Herald today I run through the reading of the rules. Homecoming adult children, I say, become child adults, children first again, and the impact on crotchety old parents can be, well, unsettling.

Six years ago the Australian Unity Wellbeing Index found in a national survey that children at home had a significantly different impact on parents below and above age 56. Below 56 the presence of adult children in the parental home had no effect on the parents' wellbeing, but above 56 the effect was dramatic. Parents older than 56 who continued to live with their children "fail to experience the upward surge in wellbeing normally experienced by people older than 56 years", the researchers found. My wife and I are 56, by the way.

Of course we enjoy and appreciate contact with our children, and one of the main aspects of that is seeing them off into the wide world as independent adults. And it's good to be able to offer a base. For a while. From time to time.

I had been hoping we'd trade our big house for a small house as my children moved out until my wife decreed a few months ago that we'd always need a big house to accommodate "the children when they come home". And how could we house them in a small house, she asked rhetorically, when they come home to stay with their children!

I don't know why but young adults don't seem to see separation from the parental home as crucial to independence and adulthood as we did a few decades ago. Any ideas?