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1 October 2014
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Don't be surprised if you can't remember deciding whether to be left- or right-handed. Hand preference is thought to begin in your mother's womb and stay with you for life.

Two knights fighting
Left-handers may have an advantage in combat.

And what comes naturally to us is important information for scientists. Handedness may be a clue into our behaviour and the way our bodies work.

Our brains are contra lateral, meaning that the left hemisphere controls the movement of the right side of our body and the right hemisphere controls the left side of our body. A left-handed person will therefore be right brain dominant while a right-handed person will be left brain dominant.

Studies have suggested that a 'lefty' may be more talented in areas thought to be controlled by the right side of the brain – spatial awareness, maths and architecture. Right-handers may have better verbal abilities because the left hemisphere of the brain is generally more efficient in processing verbal information. However, this theory is highly controversial and it is by no means set in stone. Other studies have shown that left-handers perform just as well in functions controlled by the left side of the brain.

Better in a fight?

What is known is that about 10–14% of the world population is left-handed and men are twice as likely to be left-handed as women.

Left-handers have long been persecuted but some scientists believe that they have at least one advantage over right-handers. They may be more likely to come out on top in hand-to-hand combat or sports like cricket or baseball.

A man and a woman
A BBC One television series Secrets of the Sexes explores brain sex differences.

This may be because there are fewer left-handers, so when a right handed person (who is used to fighting mainly right-handers) encounters a left-hander, he is overwhelmed by the unfamiliar experience.

Or it may be that hormones play a part. There is a theory that, on average, left-handed people are exposed to higher levels of the male sex hormone testosterone in the womb. High levels of testosterone are linked with more assertive behaviour.

It's possible that handedness is hereditary. The British Royal family has a large number of left-handers, including Princes Charles and William. Other famous lefties include: Napoleon, Gandhi, Bill Clinton, Picasso, Leonardo Da Vinci, Judy Garland, Paul McCartney, Charlie Chaplin, Robert DeNiro, Maradona and John McEnroe.

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Find out about the BBC One television series Secrets of the Sexes

Read about the Sex ID experiment

Sex ID frequently asked questions

Other Sex ID articles:

Brain sex
Spatial tests
Facial attractiveness
Empathising and systemising

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