Why the hell is that so important to you? I'm personally a lot more annoyed with faux "Norwegian" paraphernalia (a lot of which I see every day, because I live in a tourist town which wants to sell them what they want) than what people call themselves.
Because it encourages the weird cosplayers, who will then claim to be "more Italian than the Italians", which is complete nonsense.
Because it's weird fetishisation of European cultures that are both seen as superior to American culture, but also at the same time as inferior.
Because it's rooted in weird beliefs in blood magic; that DNA somehow confers culture.