The general theory of relativity states gravity is not a force, but a curvature of spacetime. The geodesic equations predict what the paths of objects will be as they follow their natural geodesic paths in either flat or curved spacetime. And they do not need a force to constrain them in these paths for they are conforming to a generalized inertia path. But as soon as some agent forces the object into geodesic deviation, inertial force is manifested in the object. In the case of a gravitational field this is called weight. What causes weight or inertial force?