Prof. Armour, the University of Nottingham's professor of human genetics, 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."
But the professors are not deterred by the lack of evidence for a strong genetic factor, concluding that these factors must be relatively subtle or weak, rather than being a matter of choice or learning.
William Brandler, of Oxford University's MRC Functional Genomics Unit and first author of the earlier study that found a genetic association, warned previously that their results did not completely explain the variation of left- and right-handedness within the human population:
"As with all aspects of human behavior, nature and nurture go hand-in-hand. The development of handedness derives from a mixture of genes, environment, and cultural pressure to conform to right-handedness."
And, as Prof. Armour emphasized, the results of this latest study present opportunities for further research.
"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."