Left Handers Club Newsletter – November 2013
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A new study has concluded that there is no single, major gene which accounts for why people are right- or left-handed. About 10 percent of people worldwide are left-handed, but the mechanisms by which people favour one hand over the other remain unclear. In an effort to learn more, researchers from Nottingham University conducted detailed genetic analyses of nearly 4,000 twins who had been studied by the London Twin Research Unit in the United Kingdom. There is little doubt that left-handedness runs in families and that identical twins are more similar in their handedness than non-identical twins. They had hoped to see a difference in the gene variants of twins who were left and right handed but did not find any single gene which could account for the differences in a statistically significant way. Crucially they also calculated the statistical power of their data, and were confident that had there been a single major gene then they could have found it.
The study was published recently in the journal Heredity. Even though they didn’t find a strong genetic influence on handedness, the researchers noted that it is widely believed that handedness is not just the result of choice or learning. Therefore, it is still likely that genetic factors play at least a minor role in determining handedness and the probability is that there are many genes, all with small effect.
Professor Armour said: 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.â€
This situation is very similar to many other complex characteristics which are being studied genetically at present, including height, weight, cognitive abilities, and even whether the heart is on the left side or the right side.
A previous study done at Oxford University did find some links between handedness and a particular gene that controls left and right side development in embryos. However the authors warned that their results did not completely explain the variation of left- and right-handedness within the human population. William Brandler, of Oxford University’s MRC Functional Genomics Unit, said “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.”
The interesting thing about this study is that it might have found a gene which is related to how strongly handed people are, be it that they are right or left handed. The same gene has also been implicated in a separate study from Germany.
Left Handers Club comment:
Well, not much change there then and we still do not have any definitive link between genetics and left-handedness. What we do know from our own experience and from surveys and member feedback is that people ARE BORN left-handed and do not just learn it from their parents and others. We also know that left-handedness DOES run in families, though not in a predictable way. These facts would seem to indicate that there IS a strong genetic link, but it clearly does not show up in an easily identified way!
Note from Keith – Professor Chris McManus, author of the excellent book Right Hand Left Hand was involved in the Nottingham study and I am grateful to him for reviewing my article and making valuable clarifications and improvements. he also kindly said “Your LHC comment at the end strikes me as entirely fair and accurate!”
For those of yo that want to know more, Chris also sent me another far more detailed paper he has written on this subject and there is a link to it at the end of the post of this article online on our website.
If you have any views on this or more information to share, please add a comment to our online version of this article.
If you are still not sure what to get for the lefthanders in your life, here are our top picks, but first…
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We were contacted recently by Carmelo Castiglione, an optometrist with an interest in sports vision. He is doing a study to try to determine the left of left and right eye dominance among left-handers and to see if that influences the sports they play and how successful they are.
He has put together a short survey and a simple test to determine your eye dominance and would very much appreciate it if our Left handers Club members would complete it. He will share the results of his analysis and further research with us when they are available.
You can find his survey here:
and his video on testing your eye dominance is here:
(he suggests that if you wear glasses to play your preferred sport, you do the test wearing your glasses).
We have done a survey over a number of years on left-handedness and which hand, foot etc is dominant and you can see our results here:
Taking the eye you would use to look through a telescope as an indication of eye dominance, 75% of all left-handers are left-eye dominant. It will be interesting to see how Carmelo’s survey compares.
A lot of what we do at The Left Handers Club is trying to help left-handed children who may be struggling with basic tasks like writing because of their handedness and also to educate parents and teachers in the small changes they can make that will result in huge benefits for the children. It is always great to hear success stories and we had an email this week from Joanne that we have reproduced in full below:
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