The Seinfelds are an attractive bunch. But, um, what's up with the one kid in the green shirt? Too good to fake-smile like the rest of his family? What is he, the rebel Seinfeld? The one who's gonna grow up to be in a biker gang and ride around harassing old men and seducing good girls in bobby sox who dream of escaping their dreary small town existence on the back of a hog?