This just in: Professor Gates is half Irish,

and 75% full of shit.
In a PBS series on African-American ancestry that he hosted in 2008, Gates discovered his Irish roots when he found he was descended from an Irish immigrant and a slave girl.

He went to Trinity College in Dublin to have his DNA analyzed. There he found that he shared 10 of the 11 DNA matches with offspring of Niall of the Nine Hostages, the fourth century warlord who created one of the dominant strains of Irish genealogy because he had so many offspring.
That would make him a small part Irish, not half; and you ever notice how when something like this comes out they're never related to a cattle thief from the next kingdom over?

And, since The Obama can't possibly be outclassed by a mere professor, I wonder if we'll hear that, through his mother, he's a direct descendant of Cuchullain? Or Brian Boru? Either of whom would probably come out of his grave to disavow ANY connection with him?