  We present an SU(12) unification model with three light chiral families,
avoiding any external flavor symmetries. The hierarchy of quark and lepton
masses and mixings is explained by higher dimensional Yukawa interactions
involving Higgs bosons that contain SU(5) singlet fields with VEVs about 50
times smaller than the SU(12) unification scale. The presented model has been
analyzed in detail and found to be in very good agreement with the observed
quark and lepton masses and mixings.
