Large Lepton mixing in seesaw models - Coset-space family unification

We show that the large mixing between nu(mu) and nu(tau) observed by the Su perKamiokande collaboration is a quite natural prediction in a large class of seesaw models. This large mixing is basically due to the unparallel fami ly structure suggested from the observed mass hierarchies in quark and lept on mass matrices. We show that the unparallel family structure is automatic ally realized in "coset-space family unification" model based on E-7/SU(5) x U(1)(3) This model also suggests the small angle MSW solution to the sola r neutrino problem.