  We show that if two of four generations of the bi-spinor Standard Model are
mass-degenerate or sufficiently close in mass only three generations can be
observed. We argue that the Standard Model and its bi-spinor analog are
indistinguishable on the level of the electroweak precision variables S, T, U.
As a result the bi-spinor Standard Model, which describes experimental observed
textures of flavor mixing matrices is a better fit to the data then the
Standard Model, where the textures are arbitrary.
