Good answers, all. But to give the guy the correct answer, the rules were relaxed for a time back then.
If you were Italian on your father's side, that was considered enough. And Junior Gotti wasn't the only one they relaxed this rule for. This was especially prevalant with the sons of made guys who were married to non-Italian women. Craig DePalma's mother, Teri, is Jewish. Yet his father, Greg, saw to it that he was made before he turned 25 years old, despite the fact that he was never an earner. The kid lived in his father's house in Scarsdale until the day he went to prison (and eventually hung himself).
Supposedly the rules were tightened up again a few years ago, and you now have to be 100% Italian to get made, but I wouldn't bet on it. If you're bringing in enough money, and you have an Italian last name, I can see them looking the other way.