Jay Z isn't under any legal obligation to prove anything to this man. If he's really interested in knowing the truth he should hire a genealogist who can trace his biological history. Im sure someone in Jay's family has an ancestry or 22andme account. Otherwise this young man should save himself some time and further anguish and just move on. Life isn't fair. Many people will never get the answers they seek. It's an unfortunate reality. The sooner he accepts this, the better.