What determines if you’re right or left-handed
Queensland researchers have given the world a better grasp on the genetics of being left-handed, right-handed or ambidextrous in the largest study of its kind.
The researchers have identified 48 genetic markers related to handedness - 41 linked to being left handed and seven that influence ambidexterity, when people use both hands equally well.
Geneticist Sarah Medland, of QIMR Berghofer Medical Research Institute, a senior author on the study, said they analysed genetic data from more than 1.7 million people worldwide.
"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," Professor Medland said.
"Handedness can influence brain structure and the way different functions are located within the brain."
Before the study, published today in the scientific journal Nature Human Behaviour, fewer than a handful of the genetic variants that influence handedness had been identified.
The rate of left-handedness differs across countries from about three to 12 per cent. In Australia, the UK and the US left-handedness occurs in about 10 per cent of the population.
Despite the identification of four dozen genetic variants influencing handedness, the Queensland-led research found environmental factors are more important than DNA in determining which hand a person prefers to use.
Professor Medland said handedness could be influenced by something as simple as a baby watching what hands their parents prefer to use, or having cups more frequently placed in front of their right side as a young child.
But studies have also found that hand preference is observed by foetuses in the womb in terms of thumb sucking and waving their arms about, most preferring their right side.
University of Queensland statistical geneticist David Evans, another senior author on the study, said that when it came to ambidexterity, a factor such as injuring a hand may play a strong role in developing a person's ability to use both hands equally well.
First author on the paper Gabriel Cuellar-Partida, formerly of UQ's Diamantina Institute, said the study highlighted the number of people needed to understand genetic factors influencing complex neurological traits and conditions.
The handedness study is one of the largest genetic investigations of a complex trait ever conducted.
"These large numbers of participants provide the statistical power to detect the effect of genes," said Dr Cuéllar-Partida, who now works for private genomics company 23andMe.
Originally published as What determines if you're right or left-handed