theory that blood type is linked to personality (and other mental and
physical qualities) is popular mainly in Japan, though it has carried
over to Taiwan and South Korea. It was started by the Germans in 1901,
who, after the discovery that certain races are more likely to be predominantly of certain blood types—such as Asians being more likely than other races to be type B—used the theory to "scientifically"
explain Aryan genetic superiority.
theory experienced a popular resurgence in 1927, when Takeji
Furukawa, a professor at Tokyo Women's Teachers School, published a
paper entitled "The Study of Temperament Through Blood Type" in the
journal Psychological Research. After failed militaristic and
social experiments, the unscientific nature of the theory was widely
understood, and it lost popularity during the 1930's.
It was revived
again in 1971 by Masahiko Nomi's book Understanding Affinity Through Blood Type.
Nomi was a lawyer and journalist with no medical training or
background. Despite Nomi's lack of scientific proof, anecdotal basis,
and unclear methods, as well as constant attacks on the theory from the
medical and psychological communities, the theory is still very popular in
Japanese celebrities frequently include their blood type in their profiles, along with
age and hobbies. It is frequently included in character descriptions in
manga, television shows, and video games. Apart from the more
standard services, Japanese matchmaking services frequently
include blood type as a consideration. It is also common for people to
exchange their blood types when meeting, and some consider it unusual for a person not to know.