Ever since I was born, I'd lived with an American family. They were missionaries from Atlanta and they lived with me and my family for over 14 years. So I literally grew up with their kids and they taught me English and my brother and I would teach them Portuguese (I'm Brazilian btw). They went back to Atlanta in 2010 and I sign up for an English school just to get a certificate or a diploma or something to prove that I speak English.
Later on, I got a scholarship to study high school in Canada for 6 months, only to find out that everybody, literally everybody, I talked to would presume I was American. Some people would even argue with me.
So anyways, ever since I came back, I've been working as an English teacher, I mostly teach kids and advanced students. But what intrigues me is that I hear a lot of people saying they are fluent or advanced English speakers (some of them are even English teachers) and their accents is just terrible. They sure know a lot of words, grammar and can speak and talk naturally, but they all have accents. And so one time I wrote on my resume "native speaker" and all of my friends made fun of me. They still do actually. I just don't know if "fluent" is enough of word to describe my English.