Why do people have a dominant hand?
Short answer
People tend to prefer one hand because the brain and body have left-right differences. Genetic tendencies, development before and after birth, practice, and culture all appear to contribute.
How it works
The brain has two hemispheres, and movement control is not perfectly symmetrical. Differences in how the brain organizes fine movement can make one hand feel more precise or comfortable for writing, throwing, or using tools.
Handedness is not controlled by one gene. It can run in families, but development and experience also matter. Most people prefer the right hand for many tasks, while some prefer the left and others switch hands depending on the activity.
Key point
A dominant hand is a tendency, not a rule that every task must follow. Right- and left-handedness are normal forms of human variation, not a measure of ability or worth.