Blood-Type Personality
The belief that your ABO blood type predicts your personality is one of the most genuinely modern beliefs on this site — traceable to a specific 1927 Japanese academic paper, later revived and expanded during wartime, and still influential enough in Japan and South Korea today to show up in dating profiles, hiring practices, and mainstream media.
Traceable origin
Earliest known record: Tokichi Furukawa, a Japanese professor, published a 1927 paper proposing a link between blood type and temperament
Furukawa's paper is a genuinely dateable, named academic origin point, which is unusual among body-sign beliefs on this site — most of which have no single author or publication to point to. The theory was later picked up, expanded, and popularized well beyond its original academic context, including a documented period of use by the Japanese military exploring blood type in personnel assessment during the 1930s and 1940s.
A named academic origin, unusual for a belief this widespread
Tokichi Furukawa, a professor in Japan, published a 1927 paper proposing that ABO blood type correlated with personality traits — a specific, dateable, named academic starting point that most folk beliefs on this site simply don't have. That academic origin matters for understanding why this belief looks and functions differently from older folklore: it began as a formal (if ultimately unsupported) scientific hypothesis rather than as oral tradition slowly accumulating over centuries, which is part of why it's spread and evolved in such a modern, media-driven way ever since.
A wartime revival gave the theory unusual institutional weight
The theory saw a documented period of renewed attention during the 1930s and 1940s, including reported interest from Japanese military and organizational contexts exploring blood type as a personnel assessment tool — a genuinely unusual chapter for what would otherwise read as a light personality-quiz belief. That institutional-level engagement, even though it didn't produce lasting scientific validation, likely helped cement the theory's cultural legitimacy in Japan well beyond what a purely popular, magazine-quiz-level belief would typically achieve on its own.
Real, documented modern consequences
Unlike most of the folk beliefs collected on this site, blood-type personality typing has measurable, reported effects on real decisions today: dating apps and matchmaking services in Japan and South Korea have incorporated blood type as a compatibility factor, some hiring and team-assignment practices have reportedly factored it in informally, and Japanese media regularly produces blood-type-based personality content treated with a level of everyday seriousness that a comparable Western horoscope column usually isn't given. That combination — a specific, recent academic origin plus real, present-day social consequences — makes this one of the more unusual entries on the site, sitting closer to modern pop-psychology than to inherited folklore.
What the actual science says
Modern psychological research has repeatedly failed to find a reliable, replicable link between ABO blood type and personality traits — blood type is determined by inherited antigens on red blood cells, a purely biological classification with no established mechanism connecting it to temperament or behavior. The belief's persistence in the face of that lack of scientific support is best explained by the same combination of factors that keeps a lot of pop-psychology typing systems alive generally: broad, flattering, or vague-enough trait descriptions that most people can find something to identify with, reinforced by decades of cultural repetition and media content.
Discrimination based on blood type is a genuine, documented concern
Because the belief has real workplace and social consequences in some contexts, blood-type-based prejudice (sometimes called "bura-hara," a Japanese term blending "blood type" and "harassment") has been discussed as a real workplace issue in Japan, distinct from the belief's more lighthearted appearances in magazines and dating profiles.
What Different Cultures Say
In contemporary Japan and South Korea, blood-type personality typing (A methodical and reserved, B individualistic and creative, O outgoing and confident, AB complex and dual-natured, in the most common popular framing) remains culturally significant enough to appear in magazine personality quizzes, dating profile questions, and — controversially — has been documented influencing hiring decisions and workplace team assignments in some Japanese companies, despite lacking scientific support.
Frequently Asked Questions
Is blood-type personality typing taken as seriously in China as it is in Japan and South Korea?+
It has some cultural presence in China as well, though it's generally reported as less institutionally embedded there than in Japan and South Korea, where the belief's wartime and postwar history gave it a stronger, more specifically local foothold.
Did Furukawa's original 1927 paper meet scientific standards of evidence even by the standards of its own time?+
It's generally regarded by historians of the theory as a preliminary, methodologically weak study rather than rigorous science even by 1920s standards, which makes its long cultural afterlife considerably more a story about media and institutional adoption than about the strength of the original research.
Is there a Western equivalent belief with a similarly traceable, named academic origin?+
Few Western personality-typing systems have quite as clean a single named academic origin point as this one; most Western pop-psychology typing systems (certain personality inventories, for instance) have more complex, multi-author development histories rather than one dateable founding paper.