– and it changes your brain structure!
Researchers have studied the full DNA sequences of 38,000 left-handers from a total of 400,000 people on the UK Biobank records to see if they could spot any consistent differences related to their left-handedness.
They found four “hotspots” where there seemed to be genetic differences that could be of interest. These included evidence that the two halves of the brain – the left and right hemispheres – were better connected and more co-ordinated in regions involved in language for the lefthanders, possible resulting in better language skills. The study also indicated slightly higher risks of schizophrenia and slightly lower risks of Parkinson's disease in left-handed people.
This all by no means conclusive, but it is a big first step to establishing the genetic basis for left-handedness. But the best guess at the moment is that handedness is 25% genetic and 75% down to the environment (anything that's not in the genes, including the environment in the wormb). This study has found only the first 1% of that genetic component and only in a British population, so there is a long way to go!
RTE in Ireland produced a short video on it with an interview with one of the researchers, Professor Gwen Douaud, who is herself left-handed.
If you fancy some heavy reading, the study results were originally published here: