  We show that electronic correlations decimate the intrinsic ferroelectric
polarization of the recently discovered class of multiferroic manganites
RMn$_2$O$_5$, where R is a rare earth element. Such is manifest from {\it ab
initio} bandstructure computations that account for the strong local Coulomb
interactions between the manganese 3d electrons --the root of magnetism in
these materials. When including these the computed electronic, magnetic and
lattice structure of multiferroic HoMn$_2$O$_5$ results in an amplitude and
direction of polarization that is in accordance with experiment. The
microscopic mechanism behind the decimation is a near cancellation of the ionic
polarization induced by ferroelectric lattice displacements and the electronic
one caused by valence charge redistributions.
