Scientists from the University of Vienna together with psychologists from Australia came to the conclusion that people who write with the left hand, have a hormonal imbalance. The strong Pala is responsible testosterone. Even in embryos that he slows development of the left hemisphere of the brain. Studies have shown that most men – left-handers were born in winter or late fall. In the winter months is born of 8.2% of left-handers, but during from February to October, only 10.5 per cent. This discovery was made by Ulrich Tran.
His theory is that those children who are conceived in the spring are subjected to sun rays a lot more. They increase the level of testosterone. In this regard, the right hemisphere of the brain develops faster and better. Not the last role in this is the level of testosterone in the mother: the higher it is, the more likely that the child will be left-handed.
It should be noted that past studies have shown that only 2% of left-handers appear in families of right-handed. This probability increases to 17% if one parent uses the left hand. 46% are born left-handed, if both parents have dominant hand – the left.