Well, I guess hugeguy wants us to beg for the answer. To head off this begathon, I'll provide it:

SPOILER SPOILER

In the novel, Vito wants the young Sonny to be a lawyer. But the teenaged Sonny participates in a small-time stickup. Though he's not caught by the cops, Clemenza finds out about it. As Sonny's godfather, Clemenza has an obligation to report it to Vito. As I recall from the novel:

Vito rips Sonny a new orifice. But Sonny pipes up, bravely: "I saw you kill Fanucci." That statement stops Vito dead in his tracks. Vito struggles: "Don't you want to be a lawyer? A lawyer with his briefcase can steal more than a thousand men with guns." But Sonny replies: "I want to learn the olive oil business." Vito then utters his all-time famous line: "A man has but one destiny," and he puts Sonny under Clemenza's tutelege."

Now, can we move on?