  It is shown that the stratified or "doubly lopsided" mass matrix structure
that is known to reproduce well the qualitative features of the quark and
lepton masses and mixings can arise quite naturally in the context of grand
unification based on the groups SU(N) with N > 5. An SU(8) example is
constructed with the minimal anomaly-free, three-family set of fermions, in
which a realistic flavor structure results without flavor symmetry.

High Energy Physics - Phenomenology