Performance on a standardized test and winning the "paper-chase" is as objective as a 100-yard dash. We observe that blacks run faster than whites.
We observe that a very high percentage of the Harvard faculty is Jewish. Ditto, the percentage of Asians at Stanford. Is this excellence genetic or behaviorial?
Every culture is the creation of a tribe.
That's B.S. (BTW, it's also literally Naziesque. That each culture is associated with a specific tribe or ethnicity -- and that "blood" determines culture -- was the PRIMARY presupposition of Nazi ideology. See, for instance, Alfred Rosenberg's The Myth of the Twentieth Century. Without jumping to conclusions, I'm advising other freepers to keep a close eye on your rhetoric, RobbyS.)
According to your homepage you're a Texan, and therefore an American. Your own culture -- the American culture -- is the creation of hundreds, if not thousands, of tribes. Even Texas culture is a rich amalgam contributed to by many tribes (e.g. ethnic Germans, Hispanics, and whoever it was that developed barbecue).
Heck you can even go back thousands of years to, for instance, Rome, and find a multi-tribal origin of it's culture -- Etruscan and Latin -- and later deep incorporation of cultural elements from many others from Greeks (Greek culture itself also being multi-tribal) to Germans.