Left Handedness or a Disease?
People have always been puzzled by theleft handed part of their population. Namely, once people developedwriting with their left hand instead of their right one, or preferringtheir left hand over their right one for many different actions, theywere considered strange and unusual, to say the least. Moreover, lefthandedness was considered a sign of metal problems like retardation,brain damage, dyslexia, autism and many others. There are a lot lesspeople who are left handed than those who use their right hand formost of their daily activities. Amazingly, even 90% of babies startssucking on their right thumb rather than on their left one. Thus, isleft handedness a good or a bad thing, and should all left handedpeople be worried?
Left Handedness, Causes and Facts
First of all, there are suspicions thatleft handedness can be transferred genetically, through parents withthe same features. So, if both of the parents are left handed, thereis a 26% chance that their child will be left handed too. On theother hand, right handed parents have only 9% chances of giving birthto a left handed child. Finally, “mixed” conditions, where eachparent uses a different hand to achieve dailygoals, these chances are about 19%.
Another theory for left handednessinvolves testosterone levels. Namely, it is known that excessivetestosterone can reduce the growth of the left part of the brain inthe child during its mother's pregnancy. Thus, the right brain, whichcontrols the left body functions, takes things into control, so as toreplace the left one. Also, science claims to have discovered a lefthandedness gene, which is likely to cause psychotic mental disorders.
These negative speculations go so faras to consider ultrasound during pregnancy capable of affecting andharming the brain of the fetus, causing left handedness as aside-effect. In fact 30% of mentally retarded children are lefthanded, while 20% of identical twins with pregnancy complicationsseem to develop this phenomenon later in life.
Interestingly, using your left handover your right one for a longer period of time may convert you intoa left handed person. It takes about 8 months of use for this to takeplace. Also, small children tend to imitate their parents orcaretakers and their left handedness, developing as left handedthemselves. Thus social influence is as important as genetics. All inall, left handedness still remains a mystery hidden deep inside lefthanded people.