So What Exactly Is 'Blood Quantum'?

If you're Native American, there's a good chance that you've thought a lot about blood quantum — a highly controversial measurement of the amount of "Indian blood" you have. It can affect your identity, your relationships and whether or not you — or your children — may become a citizen of your tribe.

Blood quantum was initially a system that the federal government placed onto tribes in an effort to limit their citizenship. Many Native nations, including the Navajo Nation and the Turtle Mountain Band of Chippewa Indians, still use it as part of their citizenship requirements.

And tribes use blood quantum varies from tribe to tribe. The Navajo Nation requires a minimum of 25 percent "Navajo blood," and Turtle Mountain requires a minimum of 25 percent of Indian blood, as long as its in combination with some Turtle Mountain.