Researchers at Ruhr University in Bochum, Germany have found that right- or left-handedness is associated with the spinal cord in utero, not from the brain as claimed in previous studies.

Traditionally, the differences in gene activity of the right and left hemisphere in the brain might be responsible for a person's handedness.

"These results fundamentally change our understanding of the cause of hemispheric asymmetries," the researchers said in a press release on Ruhr University's website.

At about eight weeks into gestation, the hand preference develops in utero and becomes visible from the 13th week of pregnancy. The researchers analyzed the gene expression in the spinal cord during the eighth to twelfth week of pregnancy.

"Arm and hand movements are initiated via the motor cortex in the brain. The motor cortex, however, is not connected to the spinal cord from the beginning. Even before the connection forms, precursors of handedness become apparent. This is why the researchers have assumed that the cause of right respective left preference must be rooted in the spinal cord rather than in the brain," the statement further adds. The study was published in the journal eLife.