This is a question I've thought about a lot. Another one: what is the answer to "where are you from?"
I left the city where I grew up at age 25 and my home country age 28 and have never returned to live there, though I have visited frequently. Apart from my hometown, my last stop (Winnipeg, Manitoba) was "home" for the longest period (21 years). I was comfortable introducing myself professionally as being "from Winnipeg" but if people asked about my accent I would explain my personal history.
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Similar background...born/raised Winnipeg and left at about 22, then to Vancouver & Toronto..finally moving to US in '78 and this is my 'home' now. For some reason..I never really had a Cdn accent..but some word differences. Like you, few actual relatives left, go back occassionally to Wpg, and the place is not the same..weather might be though! Have duel citizenship..and thinking it would be nice to spend extended time in Victoria, BC. where a cousin lives....but find northern Nv's climate overall good and free of extremes.