Nationalism is a petty, silly thing. To suggest that I have something in common with people based purely on geographical location and (formerly) race is nonsense. They're created basically to give legitimacy to rulers who wanted control of a large economic area. The price you pay is nationalism and the ridiculous idea that slights against your nation are like personal attacks.
Milgram's experiments (1963) have little relevance to the manner in which America was founded. Basically an 'experimenter' who looked like a scientist told a participant to administer successively greater electric shocks to another person based on their inability to answer word association questions correctly. With minor encouragement, most participants delivered voltages high enough to kill the person (who wasn't
actually being shocked, of course).

The experiment was carried out in Stanford. It has been repeated all over the globe with generally similar results. In addition, other authority figures have been used, all of which work. It appears to show that everyone in all (Western) nations is conditioned from an early age to be obedient to an authority they perceive as legitimate. All you have to do to get public conformity and acceptance is appear to be legitimate as an authority.
Oh, and about your comments on America: remember that America was also founded as a
slave state, and continued to be a slave state for many years after most European countries ceased to do so. In addition, from what I've seen Americans are some of the least freedom loving (yeah, they love their own freedom to do what they want but this comes at the expense of other peoples' freedom) and most conformist society on Earth.
Where was the criticism of American foreign policy after September 11th, for example?