Actually gravity does affect massless objects. It can bend the path of light, even though photons are massless. See 'gravitational lensing' for some cool photographic evidence :).
The Higg's Boson gives mass to many particles; this might be part of what you're thinking of.
Whether gravity is described by bosons at its deepest level is strictly speaking an open question, though many models of quantum gravity treat it this way.
The Higg's Boson gives mass to many particles; this might be part of what you're thinking of.
Whether gravity is described by bosons at its deepest level is strictly speaking an open question, though many models of quantum gravity treat it this way.