I guess it all comes down to people believing, or not, whether he didn't know.

At this moment, I can't tell you what any of my family members other than my wife are up to. Hell, I don't even know exactly where more than a couple of 'em live. Every one of them could be breaking the law in some fashion for all I know and I would be totally ignorant of it. Why should I expect Obama to be any more aware than I am about what members of his extended family are doing?