I wonder how much of this is just people trying to be funny. But that aside, once again showing how different cultures need to be stressed more in education. Especially in an increasingly interconnected world where you have lifestyles clashing and in close proximity to each other.
I've been asked some of these "you're half German, how is that possible?" Is one of them. I'm half German but don't really look it. I can't tell you how many times I've had to say, "my fathers family is German and my mothers is Mexican". Hundreds, maybe thousands of times in my life. It all starts with an inquisitive look and then, "Clausnitzer's an interesting name..." Some of the examples clearly have to be jokes though IMO. At least, I hope so.
Maybe there are some answers that were trying to be funny, but honestly I wouldn't be surprised if all of these are real. As far as cultures being stressed in education, that's tough. I do think that people need to learn that their culture is not The One Real Culture, or The Correct Culture but again, this is tough. A great many languages use words that identify members belonging to it as some version of "The People" or otherwise denote dominance. I'd love to see a real world solution, but other than direct exposure, I have no idea how that might be accomplished and certainly not a massive scale. It might help to teach people how to be more open to new things. Adaptability is a defining trait of our species after all.