The only left-handed person mentioned in Tanach by name was Ehud ben Gera, one of the first Shoftim (Judges). He was from the tribe of Binyamin, about whom it says: ‘And the sons of Binyamin were appointed… 700 chosen men, left-handed’ (Shoftim 20, 15-17).

Ehud ben Gera killed Eglon King of Moav with his sword, by using a deceptive maneuver that he was able to carry out only because he was left-handed. He succeeded in entering the King’s room armed with a sword, because his scabbard was hung on his right side - which is usually a sign indicating that the sword holder doesn’t intend to use the sword. Had it been on his left side it would appear that he intended to use the sword immediately, since that is the way a sword is usually hung to allow the bearer to unsheath it quickly.

For Ehud, who was left-handed, it was ideal that the sword be hung on his right side - Eglon’s men had no idea he was left-handed so they allowed him to carry the sword into the king’s room. Thus he was fully prepared for a swift attack at the king.

The word ‘Ittur’ in Hebrew (left-handed) means ‘bind’ - the root letters Alef, Tes and Resh mean to close, to bind. ‘Ittur Yad Yemino’ – the full term for someone who is left-handed, actually refers to the fact that the left-handed person ostensibly binds his right hand in order to use his left hand as though it’s his right.

In Halacha, the concept of being left-handed is discussed in connection with the way certain Mitzvos are carried out by left-handed people, such as laying Tefillin. According to Rashi, (Menachos 37b) a person is defined as left-handed if his left hand is stronger than the right, whereas the Rosh (Menachos 37b and following in his footsteps shu”t Yabi’a Omer vol.2 section Even Ha’ezer qu. 20) and other Poskim say it is determined according to the dominant hand – the one that a person uses to carry out most of his day-to-day activities. The Shulchan Aruch rules that the action of writing is the determining factor as to which is the dominant hand. As such, nowadays someone who writes with his left hand – even if his right hand is stronger – is considered left-handed, and therefore must carry out the relevant Mitzvos in the way a left-handed person must.

Le’havdil, in the world at large there are three main parameters by which a right/left-handed person is determined: which hand is used for writing (like the opinion of the Shulchan Aruch); which leg goes up first when he leaps; and which is the favored eye for reading, peering through a hole or winking.

Between 87% to 90% of the world’s population are right-handed, and only 10% - 13% are ‘lefties’. The incidence of lefties amongst men is three times higher than that of women. Many theories abound amongst medical researchers as to what causes a person to be right- or left-handed, although no one can bring any definite proofs. In the year 2008/5768 British researchers claimed to have found the gene that causes a person to be left-handed.

Famous world personalities known to be left-handed: the Jewish scientist Albert Einstein, Bill Gates, and world leaders Napoleon and Bill Clinton.