Their customs growing up are Italian and that goes for Italian populations all over the world. Although they assimilate, after a few generations they don't leave behind their traditions and culture to the same degree as other ethnicities.
Just compare the number of little Italy's and Chinatowns to any other ethnicity in North America. Much like the Americans, the Italians are a proud bunch, which is y an American slanting some1 with Italian ancestry for supporting the azzurri is ironic and naive.
But you actually have funding for the sport. You can get a soccer scholarship in the U.S for both men and women. You have soccer only stadiums, as well as far more soccer related facilities (for during the winter).