The traditional family unit is changing dramatically with divorce rates rising, family sizes shrinking and the number of unmarried cohabiting couples increasing.
A detailed breakdown of the 2006 census published yesterday shows that falling fertility is having a significant impact on family size, with the average number of children per family declining from 2.2 in 1986 to 1.4 last year.
Living arrangements are also changing with the number of cohabiting couples growing by more than 50 per cent from 77,600 in 2002 to 121,800 last year.
Sociologists, however, point out that our proportion of cohabiting couples (which now account for 11.6 per cent of all family units) is still low compared with Scandinavian countries.
The number of same-sex couples recorded in the 2006 census was 2,090, an increase from 1,300 in 2002. Two-thirds of these were male couples.
Lone parent families also increased by about 23 per cent to almost 190,000. Central Statistics Office (CSO) officials said the rise may be due to more precise data provided under a revised question.
A decade after divorce was introduced, the number of people availing of it has risen significantly; 59,500 people said they were divorced last year, compared with 35,000 in 2002, a 70 per cent rise in just four years. Separation is more common still, with 107,000 people describing themselves as separated or divorced.
Marriage, meanwhile, continues to be popular with the number of marriages increasing by 110,600 (7.6 per cent) over the past four years. The number of single people is also increasing, however, growing by 138,600 (10.5 per cent).
As with the majority of western countries, the population in Ireland is growing older, although it is still significantly younger than most EU countries.
The average age of the population has increased by five months since the last census, rising from 35.1 years in 2002 to 35.6 years in 2006.
The census also captures how large-scale immigration has changed the ethnic and religious profile of the State.
Non-Irish nationals now account for 10 per cent of the population, the majority of whom are from the UK (112,548), followed by Poland (63,276), Lithuania (24,638), Nigeria (16,000) and Lithuania (13,319).
Muslims now represent the third largest religious grouping, behind Catholics and Church of Ireland.
The number of Muslims rose by 13,400 to more than 32,500 since the last census four years ago.
Catholics now number 3.6 million (an increase of 218,800 since 2002), while there are 125,600 members of the Church of Ireland (an increase of 10,000).
The religious grouping with the highest proportion of non-Irish nationals was Orthodox Christian, with its members mainly from Eastern Europe.
In the area of ethnicity, 95 per cent of people were white, followed by Asians (1.3 per cent) and blacks (1.1 per cent). Almost 2 per cent did not answer the question.