There's bit of a joke here because the Press and the foolish people who parrot them, tend to talk about some people as 'part-Maori'.
I have a very good friend who, when faced with the question, 'Are you part Maori?' said, cheekily.
'Yes, would you like to guess which part?'
If I saw this on a form and was the product of more than one heritage, I should probably answer with the one I felt most akin to.
Kiri Te Kanawa is Maori of mixed heritage but brought up as Pakeha and has always said she doesn't feel Maori.
I can think of only a very few reasons, one of them medical, where race matters at all.
We are people.