The family based on the traditional marital unit is on the decline, according to new research.
One in three Irish families no longer fits in with the model of a married couple, both of whom are in their first marriage.
This is one of many findings to emerge from a detailed statistical study of the structure of Irish families by the ESRI in collaboration with UCD.
The report found that alternative family structures are dominated by cohabiting couples and lone mothers. Together with first-time marriages, these four family types account for 92 per cent of families.
Of the 1.15 million children living in Ireland, 75 per cent live with two married parents, 18 per cent with a lone parent and 6 per cent with cohabiting parents.
The research also turns some old notions on their head. For example, the tradition of the male as the head of the house - and presumably better educated and qualified - no longer holds true.
In fact, among younger couples, women are increasingly better educated and more likely to be the higher earner.
The results of the findings are likely to have implications for future governmental policies affecting working mothers, work-life balance, the new rights and obligations of co-habitants.
Minister for Children Frances Fitzgerald said the report provided a valuable insight into contemporary Irish family life.
"Understanding the modern family is critical if we are to design and deliver quality services for families and children in Ireland, which is a priority for my Department," she said.