A good cliche is impossible to source, and too omnipresent to raise much thought. "my great-grandmother was a Cherokee princess" thus qualifies as a good cliche, and when I saw it used here, in DejaMorgana's writeup "America, We need to talk", it made me bring to the surface what exactly this means. It made me also think of trying to explain this to someone not raised in The United States: if a German made a quip about his second cousin being Lord of the Exchequer in Luxembourg, the connotation would certainly go over my head.
Let's break down the expression bit by bit:
- great-grandmother: How much do you know about your great-grandparents? Personally, I know a bit about mine because I met one (and only one) of them, and because I have asked my parents and grand-parents about them. I was born in 1979, though, which means that my great-grandparents lived before electronic recording devices were very common. There would have been graduation pictures and possibly some audio recordings, but for the most part, people of my generation's great-grandparents are prime targets for painting whatever fancies or information we want on to them. If you move up to great-great grandparents, the amount of information declines even more. Sometimes, the ancestor is not specified, just that it occurred some generations back.
- Cherokee: If you ask the average American to name an Indian tribe, chances are that "Cherokee" would be one of the first to be named. There is a reason behind this: the Cherokee seem to be by far the largest tribe in the United States. The Cherokee lived in the rich. humid lands of the southeast, and had a large population and a somewhat urbanized way of life. The boundary between Cherokee lands white settlement in the southeast moved slowly, so there would have been many opportunities for mixing of Cherokee and Europeans, genetically and otherwise. Of course, much of this would have taken place long before the "great-grandmother" era. However, the point is that if any Indian tribe is to be mentioned, Cherokee is a fairly reasonable one.
- Princess: I don't think I will be going out on a limb too much by saying that the fact that the relative is so stereotypically female has some racist implications. Indian women were all sweet, demure royalty, apparently, while Indian men never managed to reproduce, especially not with white women. All white women on the frontier resembled Laura Ingalls Wilder and wouldn't allow an Indian man to touch them. And as for why all Cherokee women were royalty...it makes a good story, even if "princess" wasn't even a concept that the Cherokee had.
Apart from these individual items, the Cherokee great-grandmother as a whole makes sense in terms of some other cultural desires. Most people want to have something interesting and unique about them. In America, European cultures are not seen as particularly unique or interesting, especially since many or most Americans couldn't pinpoint their ancestry more closely than to say they are from "England" or "Denmark" or "a mix". So some Indian ancestry adds a little bit of verve, as well as perhaps distancing the person from the perceived role as the oppressor. However, having a Cherokee great-grandmother comes with no obligations---it won't make anyone a target of racism--- nor does it need to be proved or demonstrated in any way. In other words, the Cherokee princess in the family tree is a way to add a dash of interest and exoticness, without having to be proved, or incurring any penalties or prejudices.
However, I should also point out that the chances that the average European-descent-looking American has some native American ancestry is probably quite high. I don't know if any systemic studies have been done, or even if such studies would be possible, but if someone has ancestors in this country going back 8 generations, it is quite possible that one of those sixty-four ancestors was native American. However, that doesn't provide any type of cultural or social connection.