The blood type personality theory is a pseudoscientific belief prevalent in Japan and South Korea, which states that a person's blood group system is predictive of a person's personality, temperament, and compatibility with others. The theory is generally considered a superstition by the scientific community. One of the reasons Japan developed the blood type personality indicator theory was in reaction to a claim from German scientist Emil von Dungern, that Blood type B people were inferior. The popular belief originates with publications by Masahiko Nomi in the 1970s. Although some medical hypotheses have been proposed in support of blood type personality theory, the scientific community generally dismisses blood type personality theories as superstition or pseudoscience because of lack of evidence or testable criteria. Although research into the causal link between blood type and personality is limited, the majority of modern studies do not demonstrate any statistically significant association between the two. Some studies suggest that there is a statistically significant relationship between blood type and personality, although it is unclear if this is simply due to a self-fulfilling prophecy. History The idea that personality traits were inherited through the blood dates as far back as Aristotle. Hippocrates also sought to link personality biologically, linking traits with the four bodily humors – sanguine, phlegmatic, choleric, and melancholic. In 1926, Rin Hirano and Tomita Yashima published the article "Blood Type Biological Related" in the Army Medical Journal. It was seen to be a non-statistical and unscientific report motivated by racism. Takeji Furukawa In 1927, Takeji Furukawa, a professor at Tokyo Women's Teacher's School, published his paper "The Study of Temperament Through Blood Type" in the scholarly journal Psychological Research. The idea quickly took off with the Japanese public despite Furukawa's lack of credentials, and the militarist government of the time commissioned a study aimed at breeding ideal soldiers. The study used ten to twenty people for the investigation, thereby failing to meet the statistical requirements for generalizing the results to the wider population. On the other hand, in 1934, Fisher announced the chi-squared test, which is very popular at present, for the first time. Several scholars said that they found statistically significant differences in analyzing Japanese work conducted at that time. In another study, Furukawa compared the distribution of blood types among two ethnic groups: the Formosans in Taiwan and the Ainu of Hokkaidō. His motivation for the study appears to have