In Japan, blood group is believed to have ties with behavior. Is there scientific evidence for it?

  • If they believe it then it will almost probably be measurably so. But only in the fact that people often become what it is that they are expect to be, just via social expectation. Whether or not people with certain blood groups are statistically more likely to be born in certain areas which again impose a social responsibility on the bodies involved, is yet another factor. Genetically it may be possible that certain blood groups bring with them slightly different patterns in brain developments, however that is a big claim. --- For this to be true, (and not just a measurable effect of Japanese Commented Feb 25, 2011 at 22:14
  • This claptrap about blood type and personality has also spread to Korea. :-( Commented Feb 26, 2011 at 0:20

2 Answers 2


There is no scientific evidence that blood group affects one's behavior or personality.

The history of this pseudoscience is interesting. Paraphrased from the Blood types in Japanese culture Wikipedia entry:

Different blood types were first identified by Karl Landsteiner in 1900, and soon after it was noted that there were different blood group distributions around the world. Sadly, this information was used for racial prejudice.

The notion of blood group affecting behavior became popularized in Japan in 1927, when 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.

Interest in this pseudoscience started to wane in the 1930s, but was revived in Japan in the 1970s with a book by Masahiko Nomi, a lawyer and broadcaster with no medical background. Nomi's work was largely uncontrolled and anecdotal, and the methodology of his conclusions was unclear.

In a nutshell, one's blood group is about as telling of their temperament and personality as is their Zodiac sign. Which is to say, not at all.

  • Scott, I suggested an edit to your answer to correct two minor issues. I think a direct quotation may have better served this answer, as some sentences in the paraphrased section are very similar to the original. Commented Feb 26, 2011 at 14:56
  • As mentioned in most sources on "Blood type theory", it is worth noting that not only is the theory complete pseudo-science, but is also rooted in a tradition of early 20th century racially-motivated "research". 1930s Japan (when the theory took off) was in many ways similar to Germany of the same era: there was a strong push by authorities to justify their imperialist and racist policies through science.
    – Dave
    Commented Apr 14, 2012 at 7:37

A good overview about this including references is given by Does blood type affect vocational behavior? by Andrew D. Carson, Ph.D. In summary it states that an influence of the blood type on the behavior can not be fully dismissed out of hand, but there are also research results which did not found any connection.

Except: (emphasis mine)

There have been a number of studies over the years testing relationships between blood type and personality, and the following brief review is illustrative rather than definitive. I provide this review purely to demonstrate that claims of a relationship between blood type and personality should not be dismissed out of hand. Early published reports (Koga & Kato, 1934; Thompson, 1936) in general found no relation between blood type and personality traits or abilities.

However, more recent research has tended to find some linkages. Rinieris, Stefanis, and Rabavilis (1980), in a large (N=600) study of normal individuals, found greater incidence of obsessional personality traits in blood types A, B, and AB than in type O. In a study of 137 graduate students, Marutham and Prakash (1990) found Type B individuals to have higher neuroticism scores (compared to types O and A) on the Eysenck Personality Inventory; there were no differences on either extraversion or Type A behavior pattern. In a small study of individuals with duodenal ulcers, Neumann, Shoaf, Harvill, Jones, and Edward (1992) reported that Type A individuals had higher trait anger, trait anxiety, and depression compared to Type O individuals on standard measures of personality.

If there are indeed relations between blood type and personality, then it is not impossible that there may also exist differences in typical blood type across occupations, and that some blood types are associated with greater performance or resistance to occupational stress than are others within given occupations. In other words, it may be possible to apply a person-environment fit theory of work using blood type as a person-attribute. However, I recommend a more thorough literature review, followed by empirical research directly testing this notion before engaging in further speculation along these lines.

I also found an journal paper which claimed a (small?) relationship between blood type and personality:

Blood Groups and Personality Traits, by R. B. CATTELL, H. BOUTOURLINE YOUNG, AND J. D. HUNDLEBY, published in the AMERICAN JOURNAL OF HUMAAN GENETICS, VOL. 16, No. 4 (DECEMBER), 1984.

SUMMARY: The High School Personality Questionnaire, Form A (10 items per factor) was given to 581 Italian or Italo-American boys averaging 14 years of age in four different cities. They were also classified for ABO types. Analysis of variance was used to detect associations between ABO type and the 13 personality factors and intelligence. An association beyond the P < .01 level was found for I factor, premsia vs. harria ("tender-minded vs. tough-minded"), A blood type being more premsic, and 0, B, and AB more harric, in that order. A relationship which appeared to warrant further investigation was personality factor J, coasthenia, with blood group AB.

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