ambidexterity, the ability to use both the right and the left hand with equal ease. Handedness is the most visible manifestation of laterality, a characteristic of the human brain that localizes certain functions to either the right or left hemisphere. The origin of handedness (or the absence of it, in the case of ambidextrous individuals) remains a matter of debate. Some researchers have posited a genetic origin, while others have suggested environmental forces; it is possible that both contribute to hand preference to some degree.