Intermarriage is very literally closing ethnic gaps in New Zealand — to such an extent that some researchers question the existence of distinct categories such as "Maori families".
"I'm very dubious of there being a 'Maori household' for the people that I know. It's a concept that I think will disappear eventually," says Wellington analyst Paul Callister.
"I think you have a continuum of people who put down that they have Maori ethnicity," he says.
"That is everything from where one person in a St Heliers household has a Maori great-grandfather through to a household in Ruatoria where everyone records only Maori ethnicity, goes to the marae and all speak te reo. They are vastly different households."
There are statistics to back Dr Callister's claim.
Two-thirds (66 per cent) of the 17,300 babies born in New Zealand last year with Maori ethnicity were also registered with at least one other ethnicity. The same applies to 50 per cent of Pacific babies, 31 per cent of Asian babies and 29 per cent of European babies.
Similarly, 69 per cent of people in couples who listed Maori as one of their ethnicities in last year's Census had partners with no Maori ethnicity, 46 per cent of Pacific people had partners with no Pacific ethnicity, 24 per cent of Asians had partners with no Asian ethnicity, and 12 per cent of Europeans had partners with no European ethnicity.
The figures are even more extraordinary for Pacific and Asian people in couples where both partners were born in New Zealand. Fully 78 per cent of such Pacific people, and 82 per cent of Asians, had partners with no Pacific or Asian ethnicity.
"While international comparisons are difficult, New Zealand's rates of ethnic intermarriage are likely to be among the highest in the world," Dr Callister says.
Yet despite the resulting overlap in official ethnic statistics, which count individuals several times if they have several ethnicities, there are still stark differences between New Zealand's four main ethnic groups.
This series has charted gaps that are closing thanks to deliberate efforts by dedicated people in health and education.
But it has also found that on the economic measures of income, employment and welfare dependency, people whose ethnicities include Maori and Pacific have done consistently worse than Europeans and Asians. This is partly because they are younger, but these gaps have not closed at all in 30 years even though the Maori and Pacific working-aged populations have actually aged faster than Europeans in that time.
In fact the employment and welfare gaps between Maori and Europeans in particular have widened, as the equalising forces in health and education have been trumped by more powerful forces worsening economic inequality: globalisation, deunionisation, tax and welfare changes, and technological shifts that have lifted demand for skilled workers and reduced demand for the unskilled.
Today's final batch of figures shows that this widening inequality translates into a measurably worsening quality of life for Maori in particular, and for Pacific people too on some measures.
Maori violent offending and imprisonment rates are an order of magnitude worse than European rates, and still rising. The Ministry of Justice says 20 per cent of Maori men who turn 39 this year were imprisoned before they turned 35, 4.2 times the non-Maori rate. Corrections Department research says this may partly reflect discrimination by police and the justice system, but primarily reflects socio-economic conditions such as family breakdown, leaving school early and unemployment.
The process is self-perpetuating because imprisonment itself helps to break up families, disrupts education and makes it extremely difficult to get a job after leaving jail.
Maori, and to a lesser extent Pacific, women are far less likely than European and Asian women to live with partners. This is partly because the men may be in jail, and partly because many have gone to Australia, but primarily because they are less likely than European and Asian men to be highly educated and employed, so the women may be financially better off without them.
Research by Dr Callister and Statistics NZ demographer Dr Robert Didham shows that partnering rates plunged for all ethnic groups when unemployment was high from 1986 to 2001. They recovered slightly in 2006 as the job market revived, but have slipped down again for all groups except European men and Asians in the latest recession.
Low partnership and employment rates, in turn, are related to home ownership rates.
Taking only the 25-44 age group to minimise differences in ethnic age structures, the ratios of both Maori and Pacific home ownership rates to European rates have fallen since 2001. Other research shows Maori and Pacific rates have fallen faster than average at least since 1991.
This matters. Maori policy consultant Will Workman says policies on home ownership and tertiary education "have more social change leverage and impact than anything else".
"Tertiary education is a proven means to increased health, wealth and life satisfaction," he says.
"Home ownership is a proven means of investment, and creates wealth retention, meaning inter-generational well-being shifts become more achievable.
"The differences in these two areas are central to understanding socio-economic differences between Maori and non-Maori. In sum, in the past most non-Maori have owned their homes, most Maori have not. This needs to change — housing is not just about social policy outcomes, it is also about economic well-being."