The reasons of the left

What do Leonardo da Vinci, Lady Gaga, Maradona and Bill Gates have in common? They are all left-handed. 10% percent of the world's population are predominantly left-sided. But why are some people born favouring one side or the other of the body? Indeed, asymmetry of the human body does not only involve only our hands: we have one eye dominating the other, we chew our food preferentially with our teeth to the right or left of our tongue and when standing still we prefer to lean on our right or left foot. A study recently published in Nature Communication might shed light on an issue that has never been fully understood. The preference for the right or left hand is established by genes and occurs immediately during the formation of the embryo in the womb. According to the study, this forced 'choice' is determined by a family of proteins, the tubulins, which guide the shaping, development and organisation of cells. 10% of people carry small variations in the genes coding for these proteins, harmless mutations that result in a preference for the left side.