Scientists Identify Genes Linked to Being Right or Left-Handed

Are you right or left handed? Genetics hold the key to determining which hand is dominant. Now, scientists have identified a biological process that influences which hand we choose to write with.

Humans are the only species to show a strong bias in handedness. About 90 percent of people are right-handed, but researchers have long wondered the actual cause of this bias. While scientists knew that it was connected to genetics, they weren't sure exactly what processes were involved.

In order to find out a little bit more about handedness, the researchers conducted a genome-wide association study. They sought to identify any common gene variants that might correlate with which hand people prefer using. In the end, they found that the most strongly associated variant with handedness is located in the gene PCSK6, which is involved in the early establishment of left and right in the growing embryo.

"The genes are involved in the biological process through which an early embryo moves on from being a round ball of cells and becomes a growing organism with an established left and right side," said William Brandler, first author of the new study, in a news release.

Previous studies have been conducted on PCSK6 in mice. Disrupting this gene in the rodents causes "left-right asymmetry" defects, such as abnormal positioning of organs in the body. For example, the mice might have a heart and stomach on their right side and their liver on their left. In addition, the researchers found that variants in other genes known to cause left-right defects when disrupted in mice were more likely to be associated with relative hand skill.

The findings reveal the role that genes play in establishing left from right in embryo development. Yet more work still needs to be done in order to completely explain the variation of handedness seen among humans.

"As with all aspects of human behavior, nature and nurture go hand-in-hand," said Brandler in a news release. "The development of handedness derives from a mixture of genes, environment and cultural pressure to conform to right-handedness."

The findings are published in the journal PLOS Genetics.