Whiteside (Agnes, Thomas Jefferson, Sarah McCreery)

Hi,
I have always been told that my great great great grandmother, Agnes Whiteside Dotson, and her parents, Thomas Jefferson Whiteside and Sarah McCreery Whiteside, were Cherokee, but did not trust the government (rightfully so) and so refused to do anything that would identify them as indigenous. Family lore says that family members alive around Dawes, specifically, refused to have anything to do with it, so that would be a Julia Dotson Prewett/Pruitt/Pruett, I suppose, if that name rings a bell for anyone.
Thomas and Sarah moved from North Carolina to Illinois at some point; Agnes was born in IL in 1817.
Anybody else related to any of them and/or know anything about any connections to anything Cherokee?

Thanks!