The structure of the traditional Irish family is shifting, according to a major new Irish study by the Economic and Social Research Institute (ESRI) and University College Dublin (UCD).
One in four Irish children under 21 now lives in a family that is not made up of a married couple, both of whom are in their first marriage the study claims.
Other family structures are made of cohabiting couples who have never been married and single mothers.
The study, called Households and Family Structures in Ireland was compiled from information contained in the 2006 Census, which has provided one of the most detailed statistical snapshots of the structure of modern Irish families.
The study, which was quoted in the Journal.ie also found that:
Among heterosexual couples, men are on average 2.3 years older than their female partner.
In more than one quarter of couples under 30 at least one partner is from outside Ireland and/or of non-white ethnicity, a dramatic demographic shift.
Gay marriage foes have lost the argument
The study found more couples with different religious affiliations than with different nationalities or ethnicities.
In heterosexual couples aged 26-40, the woman has higher educational qualifications than the man in 34 per cent of couples.
Of the 1.15 million children in Ireland, 75 per cent live with two married parents, 18 per cent live with a lone parent, and 6 per cent live with cohabiting parents.