Like most other organisms, human beings are asymmetric, although they may look symmetrical from the outside at first glance. Even during the embryonic period, the heart is formed on the left chest and the liver on the right side. Left and right lungs also have a different anatomy. The functions of the brain are also not symmetrical, which results in having right-handed and left-handed people.
Scientists have solved many questions about the causes of these variations, but some of them still remain a mystery. The dominance of the left or right side has to do with the asymmetry in the functioning of the cerebral hemispheres. In fact, one of the hemispheres is always dominant, and contains areas responsible for speech. The scientists found that the left hemisphere is dominant in more than 95% of right-handed people and the left hemisphere is dominant in about 70% of left-handed people, which is a quite confusing finding.
One of the most mysterious things that are yet to be discovered is why there are only 10% left-handed persons, and the rest 90% are right-handed. At this point you should know that variations are usually equally distributed in the population.