According to a published study, scientists explain the causes of the condition of being left or right handed: it is genetics, contrary to what has been explained about the brain link.
Stress during pregnancy, high levels of testosterone are other theories presented so far. However, this investigation appoints that being left handed is due to the asymmetric activity of the genes of the uterus, explain the authors from the University Ruhr de Bochum in Germany.
It is about the spinal cord and not the brain as known so far. The arms and hands movement begin in the governing body in an area called motor cortex which sends a sign to the spinal cord which is translated in a movement.
In the magazine Life also appoints that while the fetus is growing in the uterus until 15 weeks, the motor cortex and the spinal cord are not yet connected but it is already determined if it is left or right handed.
In other words, the fetus can already start its movements and choose a favorite hand before the brain begins to control the body.
In its article they also highlight that the asymmetric nature of the spinal cord could be due to something called epigenetics or how organisms are affected by the changes in their genes expression instead of the genes themselves.
Often, these changes are caused by the environmental influences and can affect the way the baby is growing.
And these differences in the genetic expression are the ones that could affect to the right or left parts of the spinal cord in a different way what could give place to being left or right handed.
About 10% of the world population use preferably the left side of their body, what we name left handed.