BBC News over the weekend examined a popular belief in Japan that links blood type to personality, life choices, and romantic inclinations.
The blood-type theory gained mass appeal in the 1970s when Masahiko Nomi—who has no medical background—published a book on defining personalities by blood. According to the theory:
Blood type As—who make up 40% of the Japanese population—are sensitive perfectionists and good team players;
Type Os— who make up 30%—are curious and generous but stubborn;
Type Bs— who make up 20%—are cheerful but eccentric and selfish; and
Type ABs— who make up the remaining 10%—are artsy but mysterious and unpredictable.
The popular belief has spurred an entire industry of customized products, such as soft drinks and chewing gum. The theory is also applied to everything from teaching methods in kindergarten to training Olympic athletes to assigning work projects, according to the BBC.
However, BBC News reports the belief system has also resulted in discrimination against certain blood-type minorities. Although it is illegal, many employers ask about blood type during job interview, says Terumitsu Maekawa, a professor of comparative religion at Asia University in Tokyo.
According to BBC News, Japanese scientists regularly attempt to debunk the blood-type belief, noting that blood types are just determined by proteins in the blood. Nonetheless, the theory remains popular (Evans, BBC News, 11/4).