I wouldn’t say that Americans (or Australians) are at all genetically superior to the populations they came from. In fact, it could be credibly argued that the gene pool of those who came over was inferior to those who remained. Those who came over were almost universally unable (or unwilling) to fit in to their original societies. Commercial incompetents, religious dissenters, fanatics, political undesirables, convicts, slaves, peasants, expelled crofters, “tired, … poor, …huddled masses yearning to breathe free, …wretched refuse…the homeless, tempest-tost.”
Maybe this is some of what is at the root of a bit of the “Europe Vs US” hostility that is recently going on.
Add in that we (US) were the first successful and most successful of the revolutions of the modern era to explain our ambiguous and mixed attitude toward violence.
Trouble is -- I'm an American, and I LIKE my attitude,