Why do a lot of people claim Cherokee blood but never Blackfeet blood or even Navajo blood, why it's always Cherokee but never other tribes?

My grandfather was born on a Choctaw reservation. He took me to see it when I was a small child. In spite of that, I don’t have a large amount of Native dna. My niece, on the other hand, has a significant amount of Inuit dna from her father’s side. We discovered she still has an 80 year old great aunt who lives in Canada.