http://en.wikipedia....lood_quantum_laws
Many Native American tribes did not use blood quantum law until the government introduced the Indian Reorganization Act of 1934. Some tribes, such as the Navajo Nation, did not adopt the type constitution suggested in that law until the 1950s.[5] Critics contend that because the blood quantum laws required individuals to identify as belonging to only one tribe, despite their ancestry, some lost multiple tribal memberships, and overall numbers of registered members of many Native American tribes have been reduced