One way this can happen is due to strabismus, which is a condition in which one's eyes can't converge on the same gaze point. It's often caused by problems with

One way this can happen is due to strabismus, which is a condition in which one's eyes can't converge on the same gaze point. It's often caused by problems with the extraocular muscles, which move the eyes. This reduces the brain's access to parallax information contained in image pairs that have the same gaze point in common and differ mainly due to the displacement of each eye from the other. Hubel and Wiesel showed that depriving cats of stereo cues during a critical period prevented development of depth perception based on parallax info. It may be similar for humans.