There's a scene in My Big Fat Greek Wedding where the father says that the etymology of all English words can be traced back to Greek[1]. When someone challenges him with the word "Kimono," he pauses for a second, and then concocts a semi-plausible sounding explanation about how the word evolved from a Greek word.
A comedy, but I think it does reflect how a lot of people can be so impressed by their own culture that they end up spinning fictional narratives about it. For example, I was surprised to find that a common myth among Germans was that the USA almost had German become its official language, and German only lost out by a single vote.
Pride in one's culture isn't a bad thing, but too much of it can definitely lead people to believe some very questionable claims.
[1] https://www.youtube.com/watch?v=jXt0VCPKfQ4