It used to be the received wisdom that the Irish man would not leave the family nest until middle age and then only when dragged kicking and screaming by his bride to their new home.
Those days, it seems, have not altogether deserted us, although today his affection for his mammy may not be as responsible for the delayed departure as escalating property prices.
In the six years between 1996 and 2002 the number of "children" in their twenties living with both parents has risen by some 13.7 per cent, and in their thirties, by 39 per cent to a colossal 42,500. A further 28,000 in their 30s live with lone parents. Of this age group men predominate by two to one. Little wonder then the perhaps apocryphal tales of desperate parents willing to dig deep to subsidise that first house.
Important changes in the way we lead our lives, and hence relate to each other, are reflected once again in the Third Volume of the 2002 Census of Population, published this week (http://www.cso.ie). It provides, for example, glimpses into the weakening of traditional marriage, with figures for cohabitation up by a third since the last census, while the number of lone-parent families has risen by a fifth from 125,500 in 1996 to 150,600 last year. Indeed the traditional image of a household as consisting of a married couple, with or without children, now represents only some 49 per cent of homes. These figures clearly reflect the simultaneous decline in the authority of church teaching and the rise in broken marriages.
Specific economic pressures unique to the Irish economy may be having particularly dramatic effects. The pressures on young couples of wanting to get a foot on the housing ladder and then requiring two incomes to pay a mortgage seem to have reinforced the trend of career women postponing having children. There has been a sharp increase in the number of women in relationships aged between 25 and 34 who are currently childless - now 38 per cent of the group, up ten percentage points in only six years. And there has been a rise of a third in the number of households consisting only of childless couples, whether married or unmarried (from 169,300 to 228,600).
These are very major lifestyle changes that go well beyond those usually associated with urbanisation and modernisation such as falling household and child numbers, also reflected in the CSO figures. The average number of children per family has fallen from 2.2 to 1.8 in the last 20 years, although the birth rate among immigrants may affect the figures in the next census.
Such underlying trends can be seen clearly in the disparity between urban and rural average household numbers and have important long-term implications for social policy. Not least among the elderly. The census confirms the increasing numbers living alone - nine out of 10 of the State's 436,000 over-65s live in private accommodation, and, of them, 30 per cent live on their own, a major care challenge for this ageing society.