  The origin of matter-antimatter asymmetry is one of the most important
outstanding problems at the interface of particle physics and cosmology.
Gravitational leptogenesis (baryogenesis) provides a possible mechanism through
explicit couplings of spacetime curvature to appropriate lepton (or baryon)
currents. In this paper, the idea that these strong equivalence principle
violating interactions could be generated automatically through quantum loop
effects in curved spacetime is explored, focusing on the realisation of the
discrete symmetries C, CP and CPT which must be broken to induce
matter-antimatter asymmetry. The related issue of quantum corrections to the
dispersion relation for neutrino propagation in curved spacetime is considered
within a fully covariant framework.
