Family is important to Tom Powers and it is life itself to the Corleones. Tom is the aberration in his family because he is a criminal, while Michael is the aberration in his for a time because he is not a criminal. It would be wrong to assume that the Corleones are born with criminal tendencies, however, since they are clearly acculturated to crime not by society but by their family group, which is quite a different thing from the way Tom Powers likes to be outside the norms of society.
The character of Tom Powers comes from a tough background, but the film does not blame his environment but himself for his viciousness. He is a killer and a criminal because that is what he likes to do. He is a criminal by choice, and again the fact that his brother is not and has come from the same background adds to this sense that there is something wrong in Tom from the beginning. He lives in a society that rewards his sort of behavior. It is true that his actions are illegal and that there are those who would stop him and arrest him if they could, but it is still true that he is rewarded for indulging himself in crime. He sees this as his way of achieving prominence, and he takes that route as the easiest way open to him. Tom begins by delivering beer and moves up to delivering all sorts of alcohol once it is illegal. The world in which he lives is one that has created an entire criminal class through the inept attempt at social control known as Prohibition. Much of the gang problem referred to as organized crime can be traced to Prohibition, as will be reflected in The Godfather as well. There were obviously gangs and criminals before that time, but they did not have the organization, the money, or the customer base that they had after Prohibition. The film does not make a lot out of this fact, but it is evident that Prohibition was an opportunity for criminality on a grander scale. The life of Tom Powers reflects this precisely.
Michael seems in fact to bec