  We construct a class of two Higgs doublets models with a 4th sequential
generation of fermions that may effectively accommodate the low energy
characteristics and phenomenology of a dynamical electroweak symmetry breaking
scenario which is triggered by the condensates of the 4th family fermions. In
particular, we single out the heavy quarks by coupling the "heavier" Higgs
doublet (\Phi_h) which possesses a much larger VEV only to them while the
"lighter" doublet (\Phi_l) couples only to the light fermions. We study the
constraints on these models from precision electroweak data as well as from
flavor data. We also discuss some distinct new features that have direct
consequences on the production and decays of the 4th family quarks and leptons
in high energy colliders; in particular the conventional search strategies for
t' and b' may need to be significantly revised.
