Are You Left-Handed? This Study Has Discovered Why That May Be

Are you left-handed? If you are, you make up roughly 10% of the Australian population. To explore why lefties write as they do, researchers from QIMR Berghofer Medical Research Institute and the University of Queensland analysed genetic data of 1.7 million people.

According to the ABC, researchers have discovered 48 genetic variants that influence whether a person is left-handed, right-handed or ambidextrous. 41 of these variants were linked to left-handedness, while seven were related to ambidexterity.

“Handedness is one of those things where both genetics and environment play a large role and what we’ve been able to do is advance the knowledge quite a bit further in the genetics side,” Professor Sarah Medland from QIMR Berghofer’s Psychiatric Genetics Group told the ABC.

“Each of these [variants] are just little changes in the DNA — each of them individually have very, very small effects — but when you consider all the effects together, they start to add up.”

This research is one of the largest of its kind, with researchers accessing international biobanks to analyse genetic data. The researchers found environmental factors to play a larger role in determining which hand you favour compared to genes.

“Something like height is much more strongly genetically-influenced, whereas something like handedness the genetic influences are relatively weak,” she said.

“Through training or just through interacting with the environment and using tools that are designed one way or the other, you can actually influence someone’s handedness quite a lot.”

When it comes to ambidexterity, this has different genetic markers to that of left-handedness, which came as a surprise. The common belief that lefties and those who are ambidextrous overlap doesn’t seem to be true.

“The results from our study shows there was not very much genetic overlap actually between left-handedness and ambidextrousness — it seems like there are different mechanisms going on there,” Professor Medland said.

Despite the size of this study, Professor Medland says that further research is needed into why humans develop a dominant hand and the exact influence nature and nurture play in this.

“The reason why we do this work is to help us understand ourselves as humans and this characteristic of ourselves,” she told the ABC.

“Although we’ve found 41 variants influencing left-handedness and seven influencing ambidextrousness, there’s a lot more out there to find.”

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