  It is known that Flavor Democracy favors the existence of the fourth standard
model (SM) family. In order to give nonzero masses for the first three family
fermions Flavor Democracy has to be slightly broken. A parametrization for
democracy breaking, which gives the correct values for fundamental fermion
masses and, at the same time, predicts quark and lepton CKM matrices in a good
agreement with the experimental data, is proposed. The pair productions of the
fourth SM family Dirac $(\nu_{4})$ and Majorana $(N_{1})$ neutrinos at future
linear colliders with $\sqrt{s}=500$ GeV, 1 TeV and 3 TeV are considered. The
cross section for the process $e^{+}e^{-}\to\nu_{4}\bar {\nu_{4}}(N_{1}N_{1})$
and the branching ratios for possible decay modes of the both neutrinos are
determined. The decays of the fourth family neutrinos into muon channels
$(\nu_{4}(N_{1})\to\mu^{\pm}W^{\mp})$ provide cleanest signature at
$e^{+}e^{-}$ colliders. Meanwhile, in our parametrization this channel is
dominant. $W$ bosons produced in decays of the fourth family neutrinos will be
seen in detector as either di-jets or isolated leptons. As an example we
consider the production of 200 GeV mass fourth family neutrinos at
$\sqrt{s}=500$ GeV linear colliders by taking into account di-muon plus
four-jet events as signatures.
