Presumably, it it were a complete fake, other students would have noticed that at the time.
Shadows on the shoulders? Maybe it depends on how big your head and hair are.
They put Obama between two smaller kids, so he looks freakishly large. Compared to some of the other players, he's about the same size.
But the second boy to the right has similar shadows. His head may look pasted on his shoulders, but -- hey, it's an awkward age.
A photo from another yearbook:
Focus too much on any one player and you can convince yourself that he was pasted in from somewhere else. Maybe it's the grain of the film or the fact that the players in the front are in the sun and those in the back are in the shade of the tree.
But now you have the names and can find out more about the people, who actually exist. Kam Mahi -- apparently there's only one in the whole country -- now lives in Iowa.
I like this version of the photo best, though: