How many leptons and quarks?

Based on the recently derived relation between the fine-structure constant and the Newtonian gravitational constant in a unified model of the Nambu-Jona-Lasinio type for all elementary-particle forces including gravity, I predict that there exist a dozen leptons (six neutrinos and six charged leptons) and a dozen flavors and three colors of quarks (6 \ifmmode\times\else\texttimes\fi{} 3 up quarks and 6 \ifmmode\times\else\texttimes\fi{} 3 down quarks) and that the arithmetic- and geometric-like-average masses of the charged leptons and quarks are about 35.2 GeV and 23.7 GeV, respectively.