  Neutrino mass sum rules have recently gained again more attention as a
powerful tool to discriminate and test various flavour models in the near
future. A related question which was not yet discussed fully satisfactorily was
the origin of these sum rules and if they are related to any residual or
accidental symmetry. We will address this open issue here systematically and
find previous statements confirmed. Namely, that the sum rules are not related
to any enhanced symmetry of the Lagrangian after family symmetry breaking but
that they are simply the result of a reduction of free parameters due to
skillful model building.
