For reasons yet to be fully understood, one out of ten human beings in the world is left-h

anded, and from one generation to the next, this ratio is roughly preserved. As we know, left-handedness cuts across socioeconomic, ethnic, and gender lines. Yet throughout history prominent figures in science—to say nothing of religion—have identified in left-handedness signs of viciousness or worse. In 1903, Italian physician Cesare Lombroso identified left-handedness as one of the degeneracy signs of the born criminals. Three years later, Dr. Wilhelm Fliess suggested that left-handedness was a reliable identification of homosexuality. And in 1937 British psychologist Cyril Burt declared left-handedness to be a mark of an ill-organized nervous system.

As demonstrated by all the "therapeutic" coercion that left-handed children were subjected to during the first half of the 20th century, these biases had more than just a theoretical impact. Yet even when this gauche predilection was being discouraged, handism was certainly never taken as seriously as racism or sexism now is. Perhaps it's the arbitrary nature of the trait that has militated against meaningful discrimination. After all, even when both parents are right-handed, there is still a 10 percent Chance that they will bring a left-handed baby into the world. Moreover, a white baby born in Scarsdale is just as likely to be left-handed as a black baby in Harlem. Hence when the left-handed George Bush became President of the United States, it was hardly interpreted as a blow against prejudice. Nor was much attention paid to the fact that Ronald Reagan and Gerald Ford were also southpaws.

Left-handedness is ______.

A．a thing that is cultivated

B．a thing that occurs by pure chance

C．a thing of genetic inheritance

D．a thing that occurs more in prominent figures