For many people, it is a matter of the way their brains are 'wired'. For instance, I am 'cross-lateral'. It is well-known that the right side of the brain controls muscles on the left side of the body and the left side of the brain controls muscles on the right side of the body. In general, sensory information from the left side of the body crosses over to the right side of the brain and information from the right side of the body crosses over to the left side of the brain. Not in my brain though!!! The right side of my body is controlled by the right side of my brain. This makes me slightly clumsy, absolute pants at spelling and virtually incapable of doing left and right without consciously recalling which way is which - it's almost like uploading the information into RAM! Dyslexics have similar problems. Although some people with these problems are unable to overcome them, the vast majority of us are entirely normal. Actually - and I don't include myself! - an abnormal number of genuises (Einstein being one) suffer from these kinds of brain incongruities - it forces them to think in different ways.