The harm of writing with left hand may lead to the phenomenon that patients can't write well, but it will not bring some different situations to the human body itself.
Left-handed writing is suitable for people who are seriously left-handed, write badly, and even write with their right hands; Some people have to write with their left hand because their right hand is damaged for some reason; Old people and some people who consciously practice left-handed calligraphy and exercise their left limbs to keep fit.
There are many differences between left-handed writing and right-handed writing. Left-handed calligraphy only changes the hand holding the pen, and the starting order and paragraph arrangement of words must also follow the general rules. The structure and stroke order of Chinese characters are designed based on the convenience of the right hand, so writing with the left hand requires some special skills. The most difficult thing is being right-handed, because for some reason you have to write with your left hand.
For lefties, the right hand is not the dominant hand, but it is often the hand that has to be used frequently. For right-handers, writing with the left hand is to complete a new task with almost no hands, which is naturally more difficult.
As far as IQ is concerned
Many people think "left-handed" is smarter because they see many household names are "left-handed". For example, comedian Chaplin, sexy actress Marilyn Monroe, natural scientist Einstein, Microsoft founder Bill Gates and so on.
Modern brain science believes that the left brain is the "rational hemisphere" in charge of logical thinking such as words and numbers, and the right brain is the "artistic hemisphere" in charge of image thinking such as imagination and music. Because of the phenomenon of cross-command of nervous system, people who have advantages in the left brain generally use their right hands, while those who have advantages in the right brain are generally "left-handed".
The above content source: Baidu Encyclopedia-Left-handed