Your whakapapa gives you identity and defines where you are from.
When a Maori asks you where you are from, what they are really asking is where is your whanau (family) from and not where you were born, raised or live.
It is through the place that your whanau is from that connections are made to other whanau. Other people who are related to you will be related from the place that your whanau is from and not from the place that you were born and raised.
If you were born and raised overseas, in the Maori World, you are still from the place where your whanau, and blood lines run. You still have the right to say that you are from the place where your whanau are from, even if you have never been there. The people from there may not know you personally, but they will know your whanau.
If both your parents are Maori but from two different places, make sure that you know which whanau name is from which place. For example, don't use your father's name and say you are from the place where your mother is from, as it is her name that will connect you to that place, and not your father's name.
How to find where you are from.
You need to find your whakapapa to find the answer to this question. As a general rule, if you can find out where your grandparents / great grandparents who were born in the late 1800's to early 1900's were born, this is usually the place where they are from. People born in the mid 1900's may have parents who moved, looking for work or following the urban migration trends, hence the reason why the late 1800's - early 1900's are a more accurate gauge.
Another way to find out is if you or your whanau have Maori Land shares, as the place where the land is has usually been inherited through blood and goes back to people who were from there.