It's not an American thing, this happens everywhere. I moved to London from the US a few years ago, and when I first moved here, interacting with unfamiliar cultures, I made these kind of mistakes all the time.
I thought some people might find it amusing the kind of mistakes I made. Here are a couple.
I asked my Pakistani heritage boss when he immigrated, innocently. Note I'm an immigrant to the US myself and now the UK, so I thought it was not a bad question to ask. He's British born though, and considered himself a British citizen foremost. And given the rampant racism in the UK against those of Pakistani origin (many white Brits don't consider anyone Pakistani to be "proper British"), well you could see how he might be offended at my question. Fortunately he just laughed at my rudeness.
Another time, I made a bad joke to a French colleague of mine who I'd been working with for a couple weeks. I think he said I didn't seem like a normal American, and I responded saying I didn't think he looked French, not wearing a striped shirt and a beret. Oh man, that really dug my grave right there. Saying he didn't look French was probably the greatest insult I could ever have said. He is of Turkish heritage, and Turkish people have been persecuted and treated poorly for a long time in France, including lots of racism based on "they don't look French". He was angry with me for a very long time over that. I apologized to him profusely, saying I was just an idiot American, and I think he forgave me eventually.
