According to the Huffington Post, about 10 percent of the world's population is left-handed. Handedness seems to be influenced by a combination of heredity and environment. Left-handedness appears to run in families, and some brain-structure differences between right- and left-handed people have been found.
Many famous people have been left-handed. Indiana University reports that southpaw presidents include Harry Truman, Ronald Reagan, Bill Clinton and Barack Obama. Famous musical left-handers are Judy Garland, Jimi Hendrix, Paul McCartney and Paul Simon. Carol Burnett, Tom Cruise, Whoopie Goldberg and Bruce Willis are left-handed actors. Left-handed athletes include Bruce Jenner, Dorothy Hamill, Sandy Koufax and Monica Seles.