This is What Decides Whether You'll be Left or Right Handed

Ever wondered why we favor one of our hands more than the other? One of our both hands is naturally designed to take more work load than the other (right hand in majority of the cases). According to previous science, favoring our right or left hand might be traced back to the early days of the fetus when the brain directs such movements. But a new research from Germany reveals something new. According to it, everything is linked to our spinal cord instead. Ultrasound scans have revealed that we develop a preference for the right or left hand and begin sucking the left or right thumb from the 13th week, as early as eighth week of pregnancy. Arm and hand movements are known to be initiated by the brain's motor cortex, which sends a signal via the spinal cord to turn commands into motion.Researchers at Ruhr-Universität Bochum, a public university in Germany, denied the fact that the motor cortex is not connected to the spinal cord. Head researcher Sebastian Ocklenburg explained this theory by studying the gene expression in the spinal cord during the eight to twelfth week of pregnancy. He said that it was made possible by first drawing spinal cord tissue samples from the fetus. They used a product called INVIEW Transcriptome Discover to analyze the extracted MRNA, the family of RNA molecules that transfer genetic information from the DNA to protein-making structures called ribosomes.
(Hand Dryers Spread 27 Times More Bacteria Than Paper Towels: Study)The team found clear right and left differences in the spinal cord segments of the eight-week fetuses that control arm and leg movement. Interestingly, the team traced the cause of this asymmetric gene activity and believe that epigenetic factors may be behind it. That is to say, that environmental influence may be at play. One example of this could be enzymes bonding methyl groups to DNA which in turn inhibits reading of the genes. When this process plays out to a different extent on the left and right side of the spinal cord, it means there is a difference in gene activity on either side. The researchers concluded, "These results fundamentally change our understanding of the cause of hemispheric asymmetries."  
 
The study concludes that even before the birth of a child, fetus is genetically programmed in the spinal cord for choosing one of the arms as a superior tool than the other for executing daily tasks.