Where I'm from is where I grew up. To me, that has nothing to do with my genealogy. Because we're talking about where *I* am from, not where my parents are from. I say I'm from Grenland (because I've grown up in both Skien and Porsgrunn). My father grew up in Skien but my mother grew up in rural Telemark. And I feel like I'm more "from" Oslo than from Grenland after having lived in Oslo for 6 years. This is where I feel I belong.
Of course it complicates things if you have looks that are not typically Norwegian. I have heard several people with multicultural background be annoyed if people ask them where they're from, then they reply "I'm from X" (city in Norway or something) and then people reply "yeah, but where are you *really* from?". In my mind, they would be *from* that Norwegian city. And that people mix up their questions, because what they really want to ask is where their ancestors are from.
But I mean, racist people keep saying things like "go back to where you came from". But if the person has a Norwegian citizenship, and especially if they grew up in Norway, then I'd say they're as Norwegian as I am.
I just.. I don't know why it has to be so complicated 
Well, it just is...
Nothing about my looks should betray me, unfortunately I can't hide my (barely noticeable) accent...
I've lived in Finnmark, Oppland, Telemark and Sør-Trøndelag, and people still say I'm "really" from Iceland (my citizenship) or the Faero islands (three quarters of my ethnicity) and not Norway.
My language is a mix of the dialect of those regions as well as a bit of the language used in eastern norway (because that was what immigrants learned between thirty and forty years ago when my family arrived in this country) as well as just a tiny hint of Icelandic accent that people still somehow pick up, although I have no idea whatsoever about how the heck they're able to hear anything at all in all that mess.
But apparently they do.
At least some of them.
About one third of the people I meet don't seem to notice, or at least they don't comment.