  The f(R)-gravitational theory with torsion is considered for one family of
leptons; it is found that the torsion tensor gives rise to interactions having
the structure of the weak forces while the intrinsic non-linearity of the f(R)
function provides an energy-dependent coupling: in this way, torsional f(R)
gravity naturally generates both structure and strength of the electroweak
interactions among leptons. This implies that the weak interactions among the
lepton fields could be addressed as a geometric effect due to the interactions
among spinors induced by the presence of torsion in the most general f(R)
gravity. Phenomenological considerations are addressed.
