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Why are some people left handed?

General Knowledge | 11-14 yrs | Animation, Video

There are many misconceptions about people who are left-handed. It is still rare, as 10-12% of the population are lefties. Till the mid-20th century, it was common belief that left-handedness was a defect. It is in fact, left-handed people who face difficulties as the world is not designed to cater to them. A tool as common as a pair of scissors is designed to be used by right-handed people, as are certain sporting goods and most guitars!

Is left handedness determined by genetics?

Till recently it was believed that the inheritance of left-handedness was based on your parents and their genes. Research had previously focussed on the fact that your brain is the determiner for left or right handedness. However, new research suggests that the brain is not the deciding factor in the establishment of handedness.

The science of being left handed

When a child is in its mother’s womb, by 8 weeks, they have chosen a dominant hand. By the 13th week, they are either sucking their right or their left thumbs. However, it is interesting to note that it is only by the 15th week, that the motor cortex in the brain begins sending messages to the spinal cord. If the brain and the spinal cord aren’t connected in the 8th to 13th week, how did the child choose which thumb to suck? It has been suggested that gene expressions in the spinal cord lead it to make the choice, rather than the brain.

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