JUST under half of the young adults aged 18 to 24 have never left home, mainly because they can't afford to.

The Bureau of Statistics has released a survey revealing the latest trends on family households, based on the responses of more than 30,000 Australians.

A smaller sample of 12,200 were asked more detailed questions about their expectations about marriage, whether their parents had divorced or separated during their childhood and whether they had left home.

It found almost half (47%) of the young adults aged 18 to 24 had never left home, falling to 14% for those aged 25 to 34. Although 44% cited money as the main reason for living at home, 33% said they stayed because of the "convenience or enjoyment" of living with their parents.

The survey also asked women aged 18 to 49 about whether they expected to have children, with many saying they or their partner were too old.