Unification of Generations and the Cabibbo Angle

The group-theoretical analysis of the Higgs structure of an O(14) model, which unifies generations as well as color and flavor, is presented. By using the Higgs bosons of 364 or 1716 in O(14), the famous relation between the Cabibbo angle ${\theta }_{\mathrm{C}}$ and quark masses, ${{tan}^2\theta }_{\mathrm{C}}\cong \frac{m_d}{m_s}$, can be embedded into this super unified gauge theory under some conditions on the Higgs potential.