Does dark matter consist of baryons of new stable family quarks?
  We investigate the possibility that the dark matter consists of clusters of the heavy family quarks and leptons with zero Yukawa couplings to the lower families. Such a family is predicted by the {\it approach unifying spin and charges} as the fifth family. We make a rough estimation of properties of baryons of this new family members, of their behaviour during the evolution of the universe and when scattering on the ordinary matter and study possible limitations on the family properties due to the cosmological and direct experimental evidences. 
G. Bregar, N.S. Mankoc Borstnik