10 percent of the US is left handed and that is a similar ratio to many populations around the world so it would seem to be biological.

But a new paper in the journal Heredity has ruled out a 'strong genetic determinant' in influencing handedness. 

Professor John Armour, Dr. Angus Davison (both The University of Nottingham) and Professor Chris McManus (University College London) conducted a twin study examining the whole genome of nearly 4,000 subjects from the London Twin Research Unit to compare left and right handed participants. 

They were unable to find a strong genetic factor in determining handedness. If there was a single major genetic determination of handedness, there should be a detectable shift between left and right handed people in the frequency of variants in that part of the genome — and this isn't the case.

Credit and link: University of Nottingham

Armour, Professor of Human Genetics at The University of Nottingham, said, "There should be a detectable shift between right and left handed people because modern methods for typing genetic variation cover nearly all of the genome. A survey that compared the whole-genome genotypes for right and left handed people should leave such a gene nowhere to hide." 

Despite the absence of a strong genetic factor, it is widely believed that handedness is not only a matter of choice or learning. This study suggests, therefore, that genetic factors in handedness must be relatively weak and subtle, which has ramifications for future studies.

"It is likely that there are many relatively weak genetic factors in handedness, rather than any strong factors, and much bigger studies than our own will be needed to identify such genes unambiguously. As a consequence, even if these genes are identified in the future, it is very unlikely that handedness could be usefully predicted by analysis of human DNA,"  said Armour.  

Citation:  J AL Armour, A Davison and I C McManus, 'Genome-wide association study of handedness excludes simple genetic models', Heredity , 25 September 2013, doi:10.1038/hdy.2013.93