According to statistics, every 10th person in the world is left-handed. Nowadays, this feature is not considered a deviation, but earlier they tried to retrain all children so that they write with their right hand.
Where do lefties and righties come from and https://argoprep.com/blog/what-is-digital-literacy-and-why-does-it-matter/? Our brain is designed so that the left half of the body is controlled by the right hemisphere, and the right half by the left. And this management is unequal. One of the hemispheres is always leading. 
If the right hemisphere of the brain is dominant, the person becomes left-handed.
But the differences between left-handers and right-handers do not end there. The dominant hemisphere is responsible for how we perceive and process information.
The left hemisphere is responsible for consistency, https://argoprep.com/blog/culturally-responsive-teaching-what-you-should-know/, logic, understanding the meaning of speech, abstract perception of the surrounding world. And the right one is for emotions, intuition, perception of the image as a whole.
Another question is, why does it happen that some become right-handed, while others become left-handed? Here, scientists are still looking for answers and say that this feature is laid down at the stage of intrauterine development.