Every year on August 13th, the world celebrates International Lefthanders Day, a day to recognize and appreciate the roughly 10% of people who navigate life with their left hand. But what makes left-handers so unique, and why have they always captured our curiosity?
Hand preference is still something of a mystery, likely influenced by a mix of genetics, development, and environment. Studies suggest that if both parents are left-handed, there’s about a 26% chance their child will be left-handed too. Even before birth, handedness can be predicted: research examining ultrasounds of babies sucking their thumbs found that around 90% of babies who preferred their right thumb went on to be right-handed, while three-quarters of left-thumb suckers became left-handed.
University College London’s Chris McManus, in his book Right-Hand, Left-Hand, notes that the proportion of left-handers may be increasing. He also highlights that left-handers often have brains structured to expand their range of abilities, particularly in language development. Interestingly, left-handers are overrepresented in high-IQ societies like Mensa; a 2005 study found that about 20% of Mensa members are left-handed—double the general population.
Historically, being left-handed wasn’t celebrated—it was often feared or considered unlucky. Many cultures associated the left hand with negativity. In English, the word “right” also means “correct,” while “sinister” comes from the Latin for “left.” Even today, in countries like India, Pakistan, Nepal, and parts of the Middle East, using the left hand for eating or passing objects is considered impolite.
Left-handed athletes often have an edge in sports that require strategy and surprise, such as baseball, tennis, fencing, cricket, boxing, and mixed martial arts. Left-handers are also disproportionately represented among artists, musicians, and architects—possibly due to right-brain dominance.
Left-handers have also shaped history and leadership. Seven U.S. presidents have been left-handed, with six serving since World War II: Harry S. Truman, Gerald Ford, Ronald Reagan, George H.W. Bush, Bill Clinton, and Barack Obama.
Humans aren’t the only creatures with hand preferences, though most animals show a near 50-50 split. Some exceptions include kangaroos, which tend to favor their left paw, and parrots, of which 90% prefer using their left foot to pick things up.