Seven out of 10 Australians believe a child needs to grow up in a home with both a mother and father to be happy, despite growing acceptance of single parents.

The latest World Family Map, produced by the US Child Trends research organisation, found Australians were more progressive than Asian and Middle Eastern families, but not as liberal as Europeans.

While two-parent families are still the norm around the world, a quarter of children in the US, Britain and New Zealand grow up with a single parent, compared with 18 per cent of children in Australia.

A third of births in Australia are to unmarried women, while half of all births in the UK and New Zealand occur outside marriage.

''Marriage is becoming more of an option for adults, rather than a necessity for the survival of adults and children,'' the World Family Map report states, noting that in many countries living together is a precursor or alternative to marriage.