What makes most people right-handed and others left-handed? Study finds 41 genes could be driving preferences
However, genetic influence is not strong enough to act on its own, suggesting that other factors could be at play
Is it the genes or the environment? For years, scientists are trying to solve a puzzle on what makes most people right-handed and fewer left-handed? A new study has found clues that link hand preferences to our DNA. However, genetic influence may not be strong enough to act on its own — suggesting that other factors could be at play.
Scientists found that 41 gene variants are associated with left-handedness. According to estimates, 10% of people in the US are lefties. A smaller percentage of individuals can use both their hands to carry out tasks — ambidextrous. The trait is linked to seven gene variants. These findings suggest that there is no single gene that controls left-handedness.
Professor Sarah Medland, co-senior author and head of QIMR Berghofer’s Psychiatric Genetics Group, said in a statement: "Although there is an enduring fascination with why some people are left or right-handed or both, understanding why some people are left-handed and others right-handed is also an important research question because handedness can influence brain structure and the way different functions are located within the brain."
To arrive at these findings, Prof Medland and her colleagues analyzed genetic data from more than 1.7 million people. Of these people, 194,198 were left-handed and 37,637 were ambidextrous. Further analysis pinned down preferences to 48 genes that influence whether an individual is left-handed, right-handed or ambidextrous. These genes make proteins involved in brain development. They also help the brain adapt to a changing environment, the team said.
The 41 gene variations influencing left-handedness were different from the seven identified for ambidexterity. "This suggests that ambidexterity is more complicated than we previously thought," Prof Medland and Prof David Evans, joint-senior author from The University of Queensland Diamantina Institute, wrote in The Conversation.
"Interestingly, genes that influence other asymmetries in the body, such as which side of the body the heart is located on were not associated with handedness in our study," they added.
The analysis also suggested that factors beyond genes could be driving preferences. "Environmental factors were likely to play a much more important role. This percentage was similar for ambidexterity, meaning factors such as injuring a hand or training by playing sport or musical instruments are likely to have a strong role in a person's ability to use both hands equally well," Prof Evans said.
"These large numbers of participants provide the statistical power to detect the effect of genes that have even very small effects on handedness," said first author Dr Gabriel Cuellar-Partida. "This also highlights that large studies are needed to understand the genetic factors influencing other neurological traits and conditions and why participation in research studies is so important."
"These findings give us promising new leads but more work is needed to identify further genetic variants that influence handedness. There is also a long way to go before we understand how these variants play a role in someone becoming right-handed, left-handed, or ambidextrous," researchers write in The Conversation. The study is published in Nature Human Behaviour.