But I don't think that clan fueds are to be drawn among ethnic lines. Irish Catholics have blood fueds ( and not just the Travellers), Glasgow Scots, East End Londeners, Liverpudlians, among the poorer Dutch and German communities, French Canadians, Rednecks in Texas,...there have been clan and family feuds in all of those groups. Maybe not as deeply rooted as in the communities you mentioned, but they still exist.
You are right of course. There is nothing genetic in the development of culture and western Europeans of fifty years ago would have much more of an ability to 'understand' the culture of vendetta and familial pride. In my pseudo-psychological view, the extreme individualism in Western Euro (i.e Protestant) and US culture, which is centuries old, makes it harder for people in that culture to take an insult against their uncle or sister as an insult against themselves.
In Germany, you can just leave home and never look back. In Italy, for example, you can not escape your blood and history so easily.
