The Herald data investigation also found rich Kiwis had turned their backs on God and religion, with religious New Zealanders living mainly in poor suburbs.
It also showed Wellington was the "godless" capital of New Zealand, with five in 10 people there saying they have no religion.
Census general manager Denise McGregor said today that it was encouraging to see a range of people using Statistics NZ's online discussion forum to discus the issues they cared about.
She said gender identity had emerged as one of the main talking points, accounting for over one-third of online engagement so far.
App readers: Tap here to explore the interactive
Also popular was the inclusion of "New Zealander" as an ethnicity.
"We have seen some really informed thinking -- and heated debate -- around many of the hot topics that are brought up each census cycle, such as sex, gender, sexual orientation, religious affiliation, and 'New Zealander' as an ethnicity," Mrs McGregor said.
"So far, over one-third of the online discussion has been about gender identity, but we've also had a fair bit of discussion on the data collected about transport -- in particular the number of motor vehicles people own."
Mrs McGregor said other issues where Statistics NZ was expecting people to engage had been quieter than expected.
"We're interested to hear what people think about key social issues for New Zealand today, like housing and family structures."
Statistics NZ started the online forum to encourage a wide range of people to talk about the census and shape their views ahead of a formal submission period.
The formal submission period opens today and will run until 30 June.
"The best opportunity to influence census content is to make a formal submission," Mrs McGregor said.
Statistics NZ will analyse emerging themes from the online forum alongside the formal submissions to help make decisions on the 2018 census content.
Factors such as statistical quality, and the length and complexity of the questionnaire will be taken into account before making any changes.
"The census needs to reflect the changing nature of society, and we have to balance that with being able to compare data over time and track trends."
More information about the 2018 Census can be found at http://www.stats.govt.nz/Census/2018-census.aspx