The lattice random walk theory of geminate recombination is applied to the low-field behavior of the dissociation probability η of photogenerated charge carrier pairs. It is demonstrated that this theory predicts a zero value of the slope-to-intercept ratio of η( E) for isotropic initial electron distributions, in contrast to the prediction of the Onsager continuum theory. It is further shown that the apparent slope-to-intercept ratio, given by a linear fit to data points calculated from the random walk approach, can have a wide range of values, including the Onsager value. The apparent slope-to-intercept ratio is controlled by the molecular parameters of the system. This behavior is consistent with the recent discovery of systems in which the Onsager prediction is violated.