What Causes Hand Dominance? (with pictures)

Ken Black
Ken Black
It has not been determined why most people favor their right hand.
It has not been determined why most people favor their right hand.

Hand dominance is the phenomenon that occurs when one hand is preferred over the other for fine motor skills task. It has been estimated that 85 to 90% of the world’s population is right handed. A select few individuals are known to be ambidextrous, which means they have the ability to handle fine motor skills tasks equally as well with either hand. While there has been much speculation as to what causes people to use one hand over the other, there have been no firm conclusions drawn.

Left-handed people are in the small minority.
Left-handed people are in the small minority.

Among the most common theories to explain this phenomenon is that the left side of the brain controls much of the communications functioning and therefore would be natural to control the hand an individual uses to write. The left side of the brain controls the right side of the body.

A number of questions must be answered before this can become a generally accepted theory on hand dominance. For example, if the left side of the brain is so critical in language and therefore controls the dominant hand, why is the entire population not right handed?

Children will favor one hand over the other at an early age when performing fine motor skills.
Children will favor one hand over the other at an early age when performing fine motor skills.

Some dominance also appears to be genetically determined, to a certain extent. Even if both parents are left handed, however, there is still only a one in four chance that their child will also be left handed. While that rate is higher than that of the general population, it falls far short of totally explaining the cause.

The environment can also play a role in choosing dominant hands. Desks and other writing materials are normally geared to make it more convenient for those who are right handed. This could help explain why there is so much variance among those who have left handed parents.

Many writing-related tasks can be more difficult for left-handed people due to designs intended for right handed people.
Many writing-related tasks can be more difficult for left-handed people due to designs intended for right handed people.

Further, it is possible to learn to be ambidextrous. Those who have lost a limb often have to do this, and others simply look at becoming ambidextrous as a goal to achieve. Motor skills can improve with practice, both on the preferred and non-preferred sides. In the end, hand dominance may be a product not only of biology, genetics and environment, but also choice.

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Discussion Comments

anon995245

I am sorry to tell you guys this, but I am left handed. Okay so I can learn to be ambidextrous. Sorry, no, that is not a choice. Maybe I could manage if I lost my arm but absolutely no, I am not learning to use my right hand.

When I was a child, I began writing my name completely backwards. It took me longer to learn how to even see things correctly and transfer them to my hand and duplicate it the way society wanted it. I got that far but that's it. Left handedness is not a choice, so stop trying to force people to learn how to use their right hand. That is just stupid.

anon931779

I write and eat left handed but do everything else right handed. My sister who is left handed taught me to write, so we assume that's why I write and eat left handed.

anon231232

I have a girl. She is only 11 months old and she uses her left hand. I want to know why it happened. Is there any problem?

anon181081

I'm probably more cross dominant. I write with my right. Everything else is bilateral. It actually has helped me very well as a physician and in racquetball, tennis, and martial arts. However, this phenomenon is not without an occasional quirk or disadvantage.

anon78613

The article is fairly superficial, but probably OK for the average person. Being ambidextrous should not be a goal unless your dominant hand is not functioning due to injury/stroke.

The latest research shows that persons who are ambidextrous are more likely to have learning disabilities in reading and writing, and may also be more prone to psychiatric diagnoses.

anon69283

Superficial and incomplete information about hand dominance.

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    • It has not been determined why most people favor their right hand.
      It has not been determined why most people favor their right hand.
    • Left-handed people are in the small minority.
      Left-handed people are in the small minority.
    • Children will favor one hand over the other at an early age when performing fine motor skills.
      Children will favor one hand over the other at an early age when performing fine motor skills.
    • Many writing-related tasks can be more difficult for left-handed people due to designs intended for right handed people.
      Many writing-related tasks can be more difficult for left-handed people due to designs intended for right handed people.
    • Cross dominance may be evident early in life.
      Cross dominance may be evident early in life.