There is no such thing as "citizenship," in nature, because nature does not create nations or boundaries. "Citizenship" is always and everywhere a creation of positive law.
The Framers do not agree with you:
James Madison:
http://press-pubs.uchicago.edu/founders/documents/a1_8_4_citizenships5.html
IN CONGRESS, July 4, 1776. The unanimous Declaration of the thirteen united States of America, When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.
The US Constitution make many references to Citizenship as well as NBC in this Country, I can't believe you would make such a lame argument.
You never heard of this thing called "Tribes"? I would say "tribes" are pretty natural. What "positive law" creates them?
By the way, Nation, Natural, Native, Natal, and Nativity, all have the same root word. It means "relating to birth."