Sorry to jump in Ricardo, but I couldn't leave this unanswered, my apologies. The Meeting Sonny, Tom and their father (Vito) have with the Turk (Sollozo), the drug Baron. During the meeting, after Vito had told Sollozo that he wasn't interested in his drugs business, Sonny jumped in and made a query which showed that he was interested, when instead he should have kept his mouth shut and agreed, at least in public, with his father, because he now showed that there was a separation in the family. (which is why they tried to kill off Vito because the figured that Sonny would be the new Don and take up on their deal.) And contrast to this, you never see Michael make a mistake at any of his "business" meetings. He never talks when he shouldn't and when he should talk he does, but in a reserved and contained manner.