From Genealogy.com:

Watching Out for Red Flags Many families have cherished myths and stories about their immigration to America or other pivotal events and people. Sharon DeBartolo Carmack shos you how to determine which family legends are true, and what to do if you prove one false.

"Great-grandma was a Cherokee Indian princess, you know." At the family reunion or while interviewing relatives, you might hear family stories like this or other lore about your forebears. Nearly everyone has a story that has been handed down about their ancestors. Some of these legends may be quite factual; others are myth. Almost all family stories have some grain of truth, however. Family legends aren't usually created out of thin air, and that tiny grain of truth may be the clue that leads you to genealogical success. There are many myths that have worked their way into family stories, and perhaps you've already heard some of these. Often, they are about ethnic origins or how the family came to America. If you haven't heard any of these common legends yet, make yourself aware of some of the most common ones, since you may eventually hear variations as you talk with family members.

The Cherokee Indian Princess Myth
It's always a Cherokee princess, almost never Navajo or Apache or Pueblo or Lumbee. Native American ancestry is an extremely common family story, and it seems it is always to an Indian princess. The Cherokee, of course, are a large tribe with a diverse culture, divided by the Trail of Tears. They intermarried widely, perhaps increasing the likelihood of Cherokee/white ancestry.

One reason this princess myth may have evolved is prejudice. For those who frowned upon a white male ancestor marrying an Indian woman, elevating the woman's status to princess made the truth easier to swallow. Keep in mind that any story that says you have Native American ancestry — often Cherokee — may in itself be a myth. Even though it's currently an "in" thing to have Native American ancestry, just a few decades ago, it might have been the skeleton in your family's closet. Proving certain ethnic ancestry can be difficult because of prejudice or popularity toward a culture at any given time. Throughout history, some people who were victims of prejudice may have tried to hide their native origins by changing their name or claiming a different ethnicity.