Sweigart Report: Better Know Your Blood Type | Vol. 4 / No. 12.1

Photo: Alden Chadwick, CC BY 2.0

Today in the Sweigart Report: it’s astrology with a biological bent when people try to divine personalities from blood types.

I first ran into blood type personality theory while reading Magic Knights Rayearth by CLAMP. The three protagonists introduce themselves to each other, and the first includes her name, age, grade, astrological sign … and her blood type. She hand waves it away, saying it’s in case she needs medical attention. Then I began noticing blood type being included in many manga and anime character profiles. Turns out there is pervasive, cultural idea in East Asia (and especially Japan), that blood type is an indicator of personality, temperament, and interpersonal relationships.

So what IS blood type, exactly? It’s the ABO Blood Group System, first discovered by Austrian scientist Karl Landsteiner in 19001. Blood types “are determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body.”2 It’s a genetic trait you inherit from your parents. There are the four major blood groups: A, B, AB, and O. Then each one can be positive or negative, depending on the presence of a third antigen, the Rh factor. This means there are eight blood types (and one extremely rare blood type we won’t go into here.)

By InvictaHOG (Own work) [Public domain], via Wikimedia Commons
A chart of blood types deteremined by antigens. By InvictaHOG (Own work) [Public domain], via Wikimedia Commons
In Japan, there is a well-disseminated theory that blood type dictates personality traits. It’s very similar to astrological signs in its pre-determinism of personality and compatibility. It has a history in Japanese eugenics and war propaganda of the 1930s, and it was revived in the 1970s by a Japanese journalist Masahiko Nomi who wrote some best selling books on the pseudoscience.

Here’s the break down, shamelessly taken from Wikipedia:

  • Type A
    • Best Traits: Earnest, sensible, reserved, patient, responsible, cautious.
    • Worst Traits: Fastidious, overearnest, stubborn, tense, obsessive, pessimistic.
  • Type B
    • Best Traits: Passionate, active, creative, animal loving, flexible, cheerful, optimistic.
    • Worst Traits: Irresponsible, forgetful, selfish, lazy, impatient, unreliable, “going own way”.
  • Type AB
    • Best Traits: Cool, controlled, rational, sociable, adaptable, intelligent.
    • Worst Traits: Critical, indecisive, unforgiving, two-faced, aloof, “split personality”.
  • Type O
    • Best Traits: Confident, self-determined, ambitious, strong-willed, intuitive, agreeable, competitive, athletic.
    • Worst Traits: Self-centered, cold, aggressive, unpredictable, arrogant, envious, ruthless.

There’s a short-form anime called “Blood Type ABO!” that talks about the differences. They do say that it might not be the blood type people act a certain way, but personality issues. It’s definitely an interesting watch.

While there is evidence that blood type can affect the risk of certain diseases, there is no solid evidence that it affects personality. Studies have shown weak correlation, but critics point out that it could be self-fulfilling prophecy. They have this blood type, their culture says that blood type acts a certain way, so they act that way, or identify that they act that way.

People in Japan know their blood type like Americans know their astrological signs. The Japanese will ask you what your blood type is as often as Americans ask you what your sign is (possibly even more often.) It’s a way to “know” someone and feel more secure around them. Definitely more useful to know than your astrological sign, but just as useless in determining personality. However, there is a bias. It’s prevalent enough to actually have a name: bura-hara, or blood harassment. It manifests in many different ways. Businesses can base their hiring practices and project assignments by blood types. School kids are bullied because of their blood type. The national softball team has training regimens based on your blood type. Romantic partners are judged for compatibility based on blood type. Companies create products depending on your blood type.  Here’s a nifty infographic about it. Apparently, AB is the most discriminated against.

Guess what blood type I am.

It’s not very common to know your blood type in the US, unless you donate blood or have a medical reason to know. I’ve been a member of my local blood bank since high school, so I actually know my blood type (it’s AB+). They call every few months to beg me to donate my sweet, sweet plasma, which I can universally donate. I wholeheartedly (pun intended) recommend donating blood (or plasma or platelets) regularly throughout the year if you are able to. Whole blood donations can be done every 56 days, and plasma/platelets more frequently than that. While it’s a nice thought to donate immediately after a disaster, it is much more useful to just donate consistently.

Happy Monday.

1. Because of poor communication, a lot of scientists were researching/discovering blood types around the same time, but Landsteiner appeared to be the FIRST.
2. http://www.redcrossblood.org/learn-about-blood/blood-types


Katelyn Sweigart is a recovering woonatic and This Week In Tomorrow’s new regular correspondent for your weekly dose of Monday woo.


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