For leptons we have charged leptons electron, muon, tau and uncharged leptons electron neutrino, muon nutrino, tau neutrino. For quarks we have charged quarks pairs down, up and strange, charm and truth, beauty. But we have no neutral quarks. Why? The force carrying particle for the charged particles in each case is massless. The force carrying particle for the neutral leptons is massive. By analogy why is there no massive boson triplet to couple with the neutral quarks?