Generation X New Zealanders who have a stable partner and have left the country are richer than those who are single and still living here, research shows.
People born in Dunedin in 1972-73, in the middle of the "Gen X" post-baby-boom generation, were almost four times as wealthy by age 38 if they were still partnered than if they were single.
And they were about twice as wealthy if they lived beyond Australasia than if they stayed in New Zealand. Those who went to Australia were also about a quarter better off than their contemporaries who either stayed here or came home by age 38.
These two factors had much bigger effects than either intelligence or the socio-economic status of the families people grew up in.
The research comes from a famous study following 1037 people born in Dunedin in 1972-73. Participants have been flown back to Dunedin from wherever they live every few years for interviews and health checks. Of the 1004 still alive, 756 answered enough questions to calculate their net assets at age 38.
Almost a quarter (23 per cent) were then living overseas, mostly in Australia (18 per cent), with most others in Britain.
Economist Simon Chapple, who led the wealth research, said they were not coming home as expected.
"We had 20 per cent offshore at 21. We thought people would go offshore and come back," he said. "But we had more people overseas than we expected at age 26, and they have continued to gradually leak out overseas up to age 38."
Across the whole sample by age 38, only 60 per cent owned their homes, 17 per cent owned rental properties and 6 per cent owned a holiday home. Their combined properties averaged $384,900 each, or 68 per cent of their total gross assets of $561,300.
Mortgages on those properties averaged $169,700, comprising most of their total debts of $197,100. So their net stake in property averaged $197,100, or 59 per cent of their total net wealth of $364,200.
Those with partners (72 per cent) averaged net wealth of $458,800, but those who had broken up, or had never partnered, averaged only $121,000.
Dr Chapple cited several possible reasons. "Wealthy people marry other wealthy people," he said. "Partnerships are vehicles for creating all sorts of assets ranging from kids to houses and are more efficient than singletons doing that."
People living in New Zealand were worth an average of $330,600, compared with $403,400 for those in Australia and $702,400 elsewhere.
"There is almost certainly a strong element of selection of the successful into emigration," said Dr Chapple, "as well as possible greater opportunities for wealth accumulation by living offshore."
Family start again from the bottom
Anna Milligan has done the two things researchers recommend to get rich - but real life has turned out to be more complex than theory.
Dunedin-born Mrs Milligan, 35, has spent most of her adult life overseas, where she met her American husband, Chris. But they chose to move to Wellington two years ago so their children, now aged 6 and 4, could go to school in New Zealand.
Straight after graduating from Otago University, Mrs Milligan, who was not part of the Dunedin study (main story), went to South Korea to teach English. She met her husband when he was serving there in the US Air Force.
In the US the military helped them buy a house in Georgia without a deposit, but the global financial crisis meant they sold it for little more than they owed on it and used the rest to move to New Zealand.
"So we are basically starting again," Mrs Milligan said.
In Wellington they both work and Mrs Milligan is studying part-time for a diploma in human relations.
They have a "five-year plan" to save the deposit for a house using KiwiSaver. But the average house value is already intimidating.
"I see some of my friends who have remained in New Zealand and I feel like they are a lot better established because instead of travelling they were buying houses."