Some of the least violent, least criminal types here are from the old Spanish-American families --- also the families who came in the early 1900s --- who left Mexico because of the Mexican Revolution don't seem to be much into gang activity and never were. The cholos are Mexican --- descended from a different type --- often directly from the urban slums of Mexican cities like Mexico City or Ciudad Juarez. The rancheros or campesinos from Mexico are also a better class of people.
"- descended from a different type --- often directly from the urban slums of Mexican cities like Mexico City or Ciudad Juarez."
This is a point I think most Americans do not understand. The invasion of people from over the border these days are not rural, agricultural peasants or even the Zapatistas who fought to keep their lands. They are from the city slums,who for generations have learned only to lie, cheat and steal to survive. That doesn't change because of a trip across the border.