When it became obvious my three children are all left-handed, I felt like I had conquered the gene pool. Then I began to wonder if it was nurture over nature.
The numbers defied the odds – just 10 percent of the population has a dominant left hand, yet my husband is the only right-handed person in our family of five.
Could I be teaching our kids to use their left hand?
Although I was never forced to use my right hand at school, I was once called cack-handed, I’ve always had to use scissors and can openers right-handed, and vegie peelers rarely work for me.
Yet I’ve always been aware of this special point of difference I share with a minority of the world.
By the time we are four years old we have developed a preference for using our left or right hand. When it became obvious my eldest child was left-handed, I felt proud that we were on the same page. Then my daughter started using her left hand, and I was surprised but chuffed.
When our youngest was a baby, I watched with interest to see which hand he used the most. He sucked his right thumb and I was convinced he’d be right-handed. Like his two older siblings, he used both hands for eating and scribbling till he was a few years old.
Then he developed a preference for his left hand. I wondered if I’d accidentally taught him to be a leftie. I asked his preschool teachers to leave a pencil on the table in front of him and see which hand he reached out. It was always his left.
Growing up left-handed is hardly a hardship anymore – you can buy anything from scissors and spiral notebooks to knives for left-handed people. My kids won’t always smudge their penmanship like I did.
Research even shows being a leftie may even be an advantage. Left handedness is often associated with a creative streak, and some studies have shown that lefties are up there on the genius spectrum.
But our family defies the odds, so how does handedness develop?
Looking at my family, it’d be a logical conclusion that there’s a dominant mutant gene that causes left-handedness. But is there?
It turns out handedness is still one of the mysteries of neuroscience – but there is some consensus.
It’s generally agreed that a preference for one hand over the other is likely to be determined before birth and is partly genetic, but a number of genes have been identified as contributing to variations in handedness.
Theories differ about where handedness first develops in the body.
One theory is that genetic differences between the left and right hemispheres of the brain determine whether someone is left or right handed.
A more recent theory is that handedness doesn’t start in the brain – a study published last year in the neuroscience journal eLife suggests it could stem from the spinal cord. The study suggests babies in the womb have a dominant hand before their brain starts to govern movement, and that gene activity in the spinal cord could be what first causes a person to be left or right handed.
Meanwhile, a number of studies have suggested genes are responsible for only a quarter of variance in handedness, leaving the rest to environmental factors.
That said, it’s possible I could have made my children left-handed simply by being their primary caregiver. They could have a double-whammy of the genes and social conditioning that makes it impossible for them to be righ-handed.
If a parent’s own handedness influences their child’s use of one hand over the other, right-handed parents could also be teaching their children to use the same hand.
Why there are more right-handed people than lefties is still one of science’s unsolved mysteries but at least I’m doing my part to even the odds.
World Lefthanders Day is on August 13th. Take a leftie out for a drink (just saying).