<aside> <img src="https://prod-files-secure.s3.us-west-2.amazonaws.com/549985af-7f6a-444c-bd42-bdbb1e2ce200/927845e5-6d5f-4000-a20e-e640efe502ca/IMG_3719.png" alt="https://prod-files-secure.s3.us-west-2.amazonaws.com/549985af-7f6a-444c-bd42-bdbb1e2ce200/927845e5-6d5f-4000-a20e-e640efe502ca/IMG_3719.png" width="40px" /> Blood type personality is called Ketsueki-Gata (血液型).

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Ketsueki-gata believers maintain that each of the four blood types corresponds with distinct personality traits, making different blood types more compatible with some than others. Here’s how the blood types purportedly break down by temperament.

In 1930, Japanese professor Tokeji Furukawa published a report in the Journal of Social Psychology called “A Study of Temperament and Blood-Groups.”1 In this paper, he argued that establishing a link between personality and blood type “might prove a useful basis for the objective study of temperament.”

He compared this effort to the ancient Greek physician Hipporcrates’ classification of temperaments as sanguine, phlegmatic, choleric, and melancholic, which stem from the concept known as humorism. According to this concept, four bodily fluids influence personality and behavior, but Furukawa asserted that modern classifications of temperaments typically fell into two groups: physiological and psychological. The concept of blood type personality blends the two categories together, using physiology to explain the psyche.

• People with type A blood have been linked to positive traits such as creativity, cleverness, and cooperativeness, whereas their supposed negative traits include stubbornness and uptightness. Type A individuals are reportedly more common in Japan than people with other blood types.
• Individuals with type B blood are supposed to be strong, passionate, empathetic, and decisive, but they have also been associated with selfishness and erratic behavior. People with this blood type are said to clash with those with type A blood.
• The purported strengths of those with type AB blood include rationality and adaptability, but their weaknesses are said to be indecision, criticalness, and forgetfulness. This blood type is largely viewed as having the characteristics of both type A and type B individuals. Because this blood type is rare, the people who have it are heavily appreciated in Japan.
• Type O people have been linked to characteristics such as confidence, determination, resilience, and intuition, but they are also supposedly self-centered and unstable. They are said to especially appear selfish to individuals with Type A blood.