You do understand that the Euros currently not killing each other are not the same ones who were killing each other 2000 years ago, right?
And you get that the people over here are just as much descended from the people over there as the people over there are, right?
So your theory is a like of violence in our historical past (which is a shared past with Europe) is the reason for the high murder rate in the U.S. and the lack of gun control is irrelevant?