Yes, assimilation is a big factor in the evolution of organized crime:
Every immigrant group (including today's Asians and Russians) preys on its own kind in its own neighborhoods. Irish and Jews assimilated fairly rapidly, and the next generations took advantage of assimilation to move out of the old neighborhood and to go to college, get vocational training join unions, etc.

Italians took somewhat longer to assimilate for two reasons. First, they suffered more prejudice than any other group of white immigrants--in their early years here, many Americans didn't consider them "white." Second, centuries of invasion and domination by outsiders left Southern Italians with a tradition of extreme insularity: immediate family came first, then extended family, then village--and every "outside influence" was distrusted, especially government and even secular schools.

Italian neighborhoods in American cities were clones of those villages and shared their values. In those neighborhoods, the Mob often was the employer of last resort, much like the phone company was for WASPs in Midwestern and Southern towns. Sometimes the Mob recruited a gangster with above-average intelligence who could have been successful in business, the professions or the arts if he'd had a chance--people like Frank Costello, Charlie Luciano, Carlo Gambino and Joe Accardo. But Italian-Americans have fully assimilated now. The Mafia is left with the John and Junior Gotti's, the Gaspipe Casso's...