Left-Handedness: Genes or Chance?

Is anyone left-handed in your family? My older sister is. Growing up, she always had to remind my right-handed parents to buy her special left-handed scissors, can openers, and she was always switching seats at home or in class so not to bump elbows with others at the table.

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When she was two years old, it became evident that she preferred using her left hand over her right. My European grandfather announced that her left hand should be tied behind her back so she could learn to use her right hand. But where did this antiquated notion that it’s bad or wrong to be left-handed originate?

Historical Perceptions

Throughout history, left-handed people were considered unlucky or wicked for being different from their right-handed peers. Many European languages, including English, use the word “right” and mean “correct”.

But many studies actually suggest the opposite — that it can even be advantageous to be left-handed. Since left-handed people live in a right hand dominated world, lefties are better at using their non-dominant hand versus most righties. This helps left-handed stroke victims recover faster from strokes and other related afflictions.

Studies show that when it comes to creativity and imagination, left-handed people tend to score higher. They are also reportedly good at complex reasoning, resulting in a high number of Nobel Prize winners, writers, artists, musicians, and mathematicians.

Is Handedness Genetic?

Genetics do play a part in handedness, but only some of the time. Plenty of research has been done to try and understand the complex inheritance pattern of handedness, and two single gene model theories have been proposed to date.

Handedness does not work like eye color, a classic dominant-recessive model where there is a dominant and a recessive gene. If that were the case, and we would say that if the right-hand gene was dominant over the left-hand gene, you’d be right-handed with either one or two copies of the right-hand gene or vice versa.

If that were the case, any time two lefties had a baby, the baby would turn out left-handed. In reality, this isn’t the case. It’s known that if both parents are left-handed, there’s only a 25% to 50% chance their child will be left-handed.

This raises additional questions — why is only about 10% of the population left-handed, twice as many males as females, and how do identical twins often have different handedness?

Current theories suggest that the environment plays a significant role here. Handedness is most likely due to a combination of both genes and environment while some people have a greater chance of being left-handed if their parents are. You are more likely to become left-handed based on the presence of one or more genes, but you may need an environmental trigger for it to happen.

If you do belong to the lucky 10% of the world’s population who are left-handed, know that you are in good company. Some famous lefties include Michelangelo, Raphael, Leonardo da Vinci, Renoir, Bill Gates, Oprah Winfrey, Carol Burnett, Jimi Hendrix, Alexander the Great, Dick Van Dyke, Benjamin Franklin, Henry Ford, four of the last five U.S. presidents, and Prince William.

How many lefties are there in your family?