The hand that we write with is partially determined by a handful of genes

There is a fourth category of handedness

Which is your dominate hand or can use both?

Although on the outside our bodies look symmetrical, our body movements are anything but. If you’re like most people, you write, use a phone, eat, and perform just about any task that requires tactile dexterity with your right hand. A small fraction of the population, comprising around 10% of the population, is left-handed. Rarer still are those who can use either hand with equal ease for various, though not necessarily all, tasks. These people are known as ambidextrous, with fewer than 1% of the population capable of this feat.

It isn’t generally understood why some people are ambidextrous, but the limited research conducted thus far suggests it all starts in the brain. Ambidexterity isn’t as great as it sounds either, as studies have associated ambivalent handedness with poor cognitive and mental health outcomes.

The brain is divided into the left and right hemispheres by a deep longitudinal fissure of nerves called the corpus callosum. You probably know about these hemispheres and you may have also heard that the left hemisphere handles language, learning, and other analytical processes while the right hemisphere processes images and emotions, among other things. This has inevitably led to the erroneous notion that some people who are “more logical” are left-brained while those who are “more creative” are right-brained.

Despite this enduring belief, there’s no such thing as being “right-brained” or “left-brained.” We’re actually “whole-brained” since we use both hemispheres when speaking, solving math, or playing an instrument. But that’s not to say that the brain’s two regions aren’t specialized — and the actual science of how the two halves of the brain work together may be stranger than fiction.

There is a fourth category of handedness, mixed handedness. The category describes individuals whose primary skills are divided between their hands. An example is a person who writes right-handed but throws left-handed.

In some cases, ambidextrous and mixed-handed skills develop because of job requirements or the lack of available tools designed for left-handers. The placement of controls on automobiles, scissors, can openers, levers on folding knives, and the side of hot and cold faucets on a sink are predominantly designed for right-handed individuals.

Ambidextrous people have more symmetrical brains than non-ambidextrous people. Symmetry includes both shape and function. Studies show that ambidextrous individuals are easier to sway emotionally, quicker to anger, and have a higher-than-average rate of ADHD.

There are advantages to ambidexterity, especially in sports and music. Ambidextrous players in baseball have a history of high achievement. Pete Rose and Mickey Mantle are among many players who had sizable major league careers as switch hitters.

Check Which Side of Your Brain Dominants

Playing musical instruments requires the intricate use of both hands. Musical instruments are an example of how beneficial ambidexterity can be.

Musical instruments also help develop mixed handedness in right and left-handed individuals. Drum sets, for example, are typically positioned for right-handed players. Some left-handed drummers like Micky Dolenz of the 1960s rock band The Monkees invert the positioning of their drums. However, most left-handed drummers simply play right-handed.

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