The word 'sinister' is Latin for 'left-handed.' Many ancient cultures saw left-handedness as a handicap, and would try to "convert" lefties to righties. What does Judaism have to say about being left-handed?
There is clear proof from the Torah that being left-handed is not an imperfection, and on the contrary can even be an advantage.
There was a judge who served in the high court in Jerusalem for eighty years. His name was Ehud ben Gera. The Book of Judges (3:15) describes him as being left-handed. The reason this personal detail is mentioned is that it is relevant to a fascinating story told there.
The Israelites were being oppressed at the time by the Moabite nation. Ehud came up with a plan to shake off the invaders. As leader of the Jewish people, he paid a visit to Eglon, king of Moab, supposedly to bring him a tribute from the Jewish people. But Ehud had a small sword hidden beneath his cloak. Because he was left-handed, his scabbard was on his right thigh, while most people being right-handed would have the scabbard on the left. As Eglon's guards did not see a bulge on his left side, they assumed he was unarmed and allowed him a private audience with the king. Ehud drew his sword and killed Eglon, then escaped out the window, thus ending the brutal Moabite oppression of the Jewish people in one left jab.
Ehud's left-handedness came to good use. But incidentally it teaches an interesting fact. Ehud was a judge. Jewish law stipulates that a person with any defect that may diminish the respect and dignity of his position in the eyes of the community cannot be appointed a judge. The fact that a left-handed man was a judge for eighty years shows that being a lefty was in no way seen as a defect. In Ehud's case, it made him a hero.