Ocular dominance: some family data.

The most popular aspect of ocular dominance is sighting dominance or eye preference (eyedness). It refers to the preferential tendency of individuals looking through a telescope, microscope, or keyhole, or sighting along a gun. There is little work on the relative contribution of genetic factors to ocular dominance, so it is useful to review the available data from the literature and to present some new data. Eyedness was examined in a sample of 292 biologically related parent-offspring triads and 36 sibling pairs. The incidence of right eyedness amounted to 66.1%. There was a predominance of right-eyed male subjects over right-eyed female subjects. Analysis of the family study showed a significant correlation between parents and children. The frequency of left eyedness increased continuously with the number of left-eyed parents. These results imply that a genetic influence may operate to affect the direction of eye preference, although the data do not fit any straightforward recessive or dominant Mendelian model. It is possible that they are compatible with the type of model invoking fluctuating asymmetry which has been used to explain the inheritance of other aspects of laterality.