Australian researchers have identified 48 new genetic variants which influence whether a person will be left-handed or right-handed, or ambidextrous, in the largest ever study of its kind released on Tuesday.
However, scientists remained convinced that environmental factors play a larger role than genetics in terms of influence on handedness.
The study analyzed genetic data from over 1.7 million people, identifying 41 genetic variants associated with left-handed, and seven linked with being ambidextrous.
Coming from such a large data set, the results also reaffirmed the relatively small role which genetics plays in the process, said joint-senior author, Professor David Evans from The University of Queensland Diamantina Institute.
“The results from our analyses suggested that genetic factors could only account for a small amount of the variation in handedness, whereas environmental factors were likely to play a much more important role,” Evans said.
“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.”
Study co-lead author and head of QIMR Berghofer’s Psychiatric Genetics Group, Professor Sarah Medland explained that the causes behind left and right handedness go beyond just idle curiosity.
“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,” Medland said.
Hand preference is first observed while still in the womb, with embryos showing single arm movements, according to the researchers.
The rate of left-handedness differs across countries, from around 3 to 12 percent. In Australia, Britain and the United States, the figure is around 10 percent.