Dad matters: Left hand may be just right for a daughter

If my daughter goes on to become left-handed, she will be part of a minority.

Astrid is developing sinistral tendencies. She picks up her spoon to eat with her left hand. She takes hold of a pen to draw with her left hand. She kicks a ball with her left foot. Of course, it doesn't happen every time she performs one of these actions, but she does it often enough for me to notice a predilection at this early stage in her life. If she does go on to become left handed, she will be part of a minority. Left-handedness is much less common than right-handedness. Approximately eight per cent of people are left-handed. This distinction emerges in the meanings and associations of left and right in many different cultures and religions throughout history.

Right means correct in various European languages and is often associated with justice and authority. Left has had less positive connotations for a long time. Christians have traditionally associated the devil with the left hand. The word "sinister", which has come to mean evil, ominous or unlucky, is derived from the Latin sinister, which means left. Islam teaches the distinct functions of different hands, with the right to be used, among other things, for eating and drinking and the left for removing dirt.

The reasons why asymmetry developed in humans are only starting to be unravelled. In his book, Right Hand, Left Hand, Chris McManus, professor of educational psychology at University College London, explores how we came to favour the right hand over the left. He notes that in chimpanzees, our closest relatives, there is no proven preference for a particular hand with the inclination apparently determined by chance. He goes on to explore how and why the right hand became dominant in the majority of humans.

Different hemispheres of the brain control different sides of the body. The left side of the brain controls the right side of the body, while the right side of the brain controls the left side of the body. McManus posits that our preference for the right hand is linked to the development of language, which takes place in the left side of the brain. As language developed, so the right side became more dextrous (itself from dexter, the Latin word for right), and a gene for right-handedness came to dominate.

Indeed, stone tools dated from around two million years ago are exclusively for the right hand. Somewhere between that date and 5,000 years ago, left-handed people re-emerged with a frequency that still occurs today. In 2007, five years after MacManus published his book, researchers at Oxford University found a gene for left-handedness called LRRTM1, which seems to change the way the brain develops asymmetry. This discovery confirms what has long been suspected about left-handedness running in the family.

One of the most famous examples of this inheritance is that families with the surname Kerr or Carr seemed to be much more likely to be left-handed. This belief dates back to the 14th century and a poem about a clan of left-handed swordsmen. Ferniehirst Castle, home of the Kerr clan, is one of only two castles in the UK to have an anti-clockwise spiral staircase, a defensive structure that favoured left-handed swordsmen coming down the stairs.

While a study in 1974 found that Kerrs and Carrs were more likely to be left-handed, a subsequent study in 1993 found these results to be statistically flawed. My family has a history of left-handedness. Although I am right-handed, my aunt is left-handed, as was my grandfather. We will have to wait and see if Astrid has inherited the LRRTM1 gene and become part of this distinctive club.