People who are left-handed have different genetic instructions hardwired into their brain, according to a new scientific study.
Scientists have found the first genetic instructions hardwired into human DNA that are linked to being left-handed.
Instructions also seem to be heavily involved in the structure and function of the brain, the BBC reports.
The team at the University of Oxford say left-handed people may have better verbal skills.
Studies on twins already revealed genetics has some role to play in people becoming left-handed. But the specifics are now being revealed.
The research team turned to the UK Biobank - a study of about 400,000 people who had their DNA recorded.
Scientists compared the DNA to find the regions which influenced left-handedness.
One of the researchers, Professor Gwenaëlle Douaud, told BBC News: "It tells us for the first time that handedness has a genetic component."
The mutations were in instructions for the "scaffolding" that organises the inside the body's cells, called the cytoskeleton.
Similar mutations have been found in the cytoskeletons of snails who have been shown to have anticlockwise, or "lefty", shells.
Scans of participants in the UK Biobank project showed the cytoskeleton was changing the structure of the white matter in the brain.
In the left-handed participants, the two halves of the brain were better connected and more co-ordinated in regions involved in language.
Professor Douaud said: "For the first time in humans, we have been able to establish that these handedness-associated cytoskeletal differences are actually visible in the brain."
Researchers speculate left-handed people may have better verbal skills although they do not have data from the study to prove it.
The study showed slightly higher risks of schizophrenia and slightly lower risks of Parkinson's disease in left-handed people.
