I am not sure what question you are really asking...\nThe American English morphed from British English, just ask in any language there a handful of dialects many times seperated by geographic regions and social class. (Chicago has 6 accents). So that is how Europeans can tell the difference, because your accent is not British. \n\nYou DO have an accent- even as one poster said, it could be the "non-regional"/media accent. People with a good ear for languages and dialects (usually people who are multilingual) can detect accents easier than others who are monolingual. \n\nIt also could be that you developed more of your accent of your native region since you left. For some reason, I have noticed this phenomenon with a lot of Americans after living abroad for some years. For example, I grew up in the midwest, but nobody ever believed me because they said I didn't sound like it- but the longer I have lived away from the midwest I have noticed that I sound REALLY midwestern without hearing it at all!\n\nAlso, Europeans can spot Americans a mile away... it's the way we carry ourselves-- we smile a lot more and speak louder in public and often all they have to do is look at your clothes or your feet to know.