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Blood Type Personality Theory

The Blood Type Personality Theory (血液型性格分類, Ketsueki-gata Seikaku Bunrui) is a pseudoscience with highly controversial origins, claiming that blood type can predict one's compatibility and personality. It was mostly popular in Japan and South Korea.


As nationalist propaganda

The ABO blood types were first discovered by Karl Landsteiner in 1901, then further research was done by Emil von Dungern and Ludwik Hirszfeld on heritability. During this time period, scientific racism was popular,1) so the Eugenicists obsessed with racial purity attempted to warp the research to fit their future slogans of blood and soil, asserting that certain types were “move evolved” than others.2)3)

In 1916, Kimata Hara, a Japanese doctor that studied under Durgen, would bring their research to Imperial Japan and briefly touched on linking blood types to personality.4) This was taken seriously by the military around 1926,5) eventually leading up to Takeji Furukawa publishing his paper in 1927 that formally linked blood types to personalities, enabling their military to discriminate by blood type.

As a personality theory

Following the events of World War II, his theory was left alone until people got the idea to simply remove the racial aspects of the theory, turning it into a personality diagnosis test. It's known that Léone Bourdel had published an academic paper in 1962,6) but it wasn't really popular until Masahiko Nomi published a book in 1971 that somehow became a bestseller in East Asian countries like Japan and South Korea.

Soon enough, it became a cultural phenomenon that influenced media, television segments, and became a factoid that people really wanted to know about their favorite celebrities or fictional characters. However, psychologists would quickly discover that the reformed theory made people uncomfortable as the whole thing could still create discriminatory assumptions of others despite the change.7)

However, it took decades until the theory started being phased out in the 2000s. Japan would shelve it after the Broadcasting Ethics & Program Improvement Organization deemed it a “social issue” in 2004,8) then South Korea saw the Korean Society of Hematology formally reject it in 2008.9)10) Of course, some people still believe in it to this date, but please keep in mind that its dark history isn't common knowledge.


There doesn't seem to be a major, overarching definition of the four blood type personalities, possibly to be ambiguous, so I've organized what's been said about them from various sources:

Type Dong-a Ilbo (1937) Léone Bourdel (1962) Masahiko Nomi (1971) The Guardian (2008)
O • Academic/Military.
• Calm, gentle.
• Strong self esteem.
• Business/Diplomat.
• Fine with change.
• Witty, romantic.
• “The Boss”
• Gentle with workers.
• Values connections.
• Active, confident.
• Decisive, curious.
Elizabeth II.
A • Banking/Finance.
• Cautious, reflective.
• Expressive.
• Compliant, sincere.
• More individualistic.
• Patient, curious.
• “The Leader”
• Builds framework.
• Follows rules.
• Cautious, reserved.
• Perfectionist.
Adolf Hitler.
B • Activism/Business.
• Relaxing to be with.
• Witty, sociable.
• Active, passionate.
• Emotional lover.
• Strong leader type.
• “The Director”
• Tech over people.
• Values honesty.
• Cheerful, flamboyant.
• Free thinkers.
Jack Nicholson.
AB • Mix of Type A and B. • Caring, shy.
• Complex, eccentric.
• Delicate, relaxing.
• “The Pillar”
• Strong presence.
• No instructions.
• Artistic, distant.
• High maintenance.
Mao Zedong.

As for the four stereotypes: Type A is timid, Type B is stingy and psychotic, Type AB is eccentric or lazy, and Type O has the least negatives which makes them a target for the other three blood types.


  • I want to be clear that, in case the message somehow became lost, Eugenics is a bad thing.
  • The truth about blood types is that blood type distribution is essentially random. You can see that Ecuador and Peru has a lot of Type O blood, but it doesn't affect their military personnel.
  • Recently, the theory has kinda declined in favor of alternatives like the Myers-Briggs Type Indicator.
  • For those curious, the curator has Type AB+ blood. I have not donated plasma yet.
3) , 10)
"You're type AB, right? (Studio K) | KBS WORLD TV 200910" [2:54] (September 10, 2020). YouTube.
“Regarding the Genus Structure of Blood” (血液ノ類属的構造ニ就テ), authored by “Kimata Hara” (原來復) and “Sakae Kobayashi” (小林栄), published in “Iji Shunbun, No. 954” (『醫事新聞』第954号).
“Regarding Human Blood Agglutination Reaction” (人血球凝集反応ニ就テ), authored by “Hayashi Hirano” (平野林) and “Tomita Yajima” (矢島登美太), published in “Gun'i-dan Zasshi, No. 157” (『軍医団雑誌』157号).
“Léone Bourdel” was a French psychologist who wrote an academic paper in 1962 that was titled “Blood and Temperaments” (Sang et Tempéraments).
7) , 8)
"「血液型を扱う番組」に対する要望" (December 8, 2004). Broadcasting Ethics & Program Improvement Organization.
In the Namu Wiki article, there's a clip of a scene in the 2006 film, My Scary Girl, where the protagonist angrily denounces the personality theory, noting that only Japan and South Korea still believes in it.
blood_type_personality_theory.txt · Last modified: 2024-05-17 03:38:50 by namelessrumia