What causes some people to be left or right handed?

When a kid tends to grow old, he/she most likely favor the usage of one hand over the other hand while performing some tasks. This usage of one hand over other is more prominent when it comes to writing and drawing. There are two main categories of handedness mainly right handed and left handed. The time this decision at the same time when they are in the age of acquiring language. Usually, the major selection takes place at the age of four. As the child handedness reveals a lot about the organization and function of their brain.[irp]

The human brain consists of two hemispheres the right and the left hemisphere which are responsible for controlling the motor action on the alternate side of the body. Since right and left part of the brain are not same in their control over various actions and behaviors, one hand takes lead over the other hand in performing different tasks. When one hemisphere takes dominance over the other hemisphere, for controlling certain behaviors and actions, it is termed as Lateralization.

According to research and latest theories, there are relevant evidence which confirm evolution of cerebral lateralization. On the first hand, the one hemisphere dominating the other one decreases the chance of both hemispheres fighting to take over a response. It also permits the various processes such as attention and language to work in a parallel across the two hemispheres.

For many people, the left hemisphere of the brain is the substantial one used for speech. The left hemisphere is also used to control hand actions and speech. Due to which the majority of the people are right handed when they use instruments and tools like a pen when they make gestures. As stated by the psychologists, the hand gestures and tools used play an important role in the evolution of human speech. As suggested by another theory, since vision is the primary sense, the hand gestures give birth to the human communication for the first time.

RIGHT, LEFT OR BOTH: In the mid-20th century, a scientist suggested the left-handedness to be an abnormal development. It was compared with a number of developmental functions varying from language forms and leading to mental health disorders. In fact, in the same era, many left handed children were forced to adopt right handedness to write so that they can retain the right handedness. But in the modern era, this theory has failed and the use of left handedness is not considered as an abnormal condition.[irp]

Children may use both rights and left hands equally to perform various tasks and actions. But it has been observed that majority of the children use right hand to carry out complex tasks which require specialized processing techniques. A large number of the population has the right hemisphere of the brain that is prominent to danger. Handedness is not only the basis which constitutes our motor skills which evolved from cerebral lateralization.