  We argue that presymmetry, a hidden predynamical electroweak quark-lepton
symmetry that explains the fractional charges and triplication of families,
must be extended beyond the Standard Model as to have a residual presymmetry
that embraces partner particles and includes the strong sector, so accounting
for the twin or mirror partners proposed to alleviate the naturalness problem
of the weak scale. It leads to the full duplication of fermions and gauge
bosons of the Standard Model independently of the ultraviolet completion of the
theory, even if the Higgs particle is discarded by experiment, which adds
robustness to twin and mirror symmetries. The established connection is so
strongly motivated that the search for twin or mirror matter becomes the
possible test of presymmetry. If the physics beyond the Standard Model repairs
its left-right asymmetry, mirror symmetry should be the one realized in nature.
