Sunday 19 November 2017

The genetic basis of left-handedness



The incidence of left-handedness in people is about 10%, and that appears to be fairly constant across the world. It is also known that left-handedness runs in families, which might seem to indicate that there is a gene that influences whether a child will turn out to be left-handed. The only problem is that nobody can identify the gene that might be responsible.

Where does left-handedness comes from?

A study carried out at Nottingham University conducted detailed genetic analyses of 2,000 pairs of twins, because it is known that identical twins tend to share handedness more strongly than non-identical twins. This suggests a genetic link because identical twins have identical DNA.

However, the conclusion is that there is no single gene that causes left-handedness, so it might be a combination of genes that does the trick. The same is apparently true for other human characteristics such as height and cognitive abilities. It is therefore improbable that it will ever be possible to predict whether a new-born baby will turn out to be left-handed by analysing its DNA.

However, the study does appear to have identified a gene that determines how strongly handed one is, whether left or right, and this confirms other research done elsewhere. It is rare to find someone who is entirely left- or right-handed, and there is apparently a genetic reason for this.

Being left-handed

This is an area that interests me because I am left-handed (reasonably strongly so); however, because I was adopted I cannot trace any left-handedness in my natural family, which is unknown to me. The only person I know who is a blood relative is my son, who is right-handed!

Incidentally, one thing I cannot do right-handed (apart from writing) is operate a computer mouse! I haven’t switched the buttons round because my index finger naturally wants to go to the left-hand button, and right-clicking is no problem. People know when I’ve been using a computer because of where I leave the mouse!
© John Welford

2 comments:

  1. Left-handed guitarists are left out when it comes to the choice of guitars. Music stores often have only one left-handed guitar model per 100 right hand models.

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  2. I am left-handed too! Gives me a little sense of pride as there's not that many of us, it seems like. In my family, it runs in the maternal line - my mother, aunt are left-handed, where my brother and father are right-handed.

    Like you, I write left-handed and use a mouse on the left side. However, I throw a ball and use scissors on my right side. Interesting!

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