They say blood is thicker than water.Having type O blood is a great thing. That’s something you might be told at a blood drive—but it could be a deeper compliment than you think if you’re hearing it from the right person. After all, in South Korea and Japan, different blood types are associated with different personalities. And, admittedly, some personalities attract more admiration than others.
Similar to horoscopes, blood type personality is a pseudoscience that, today, lays out basic personality traits for each blood type. According to the Korea Herald, type A’s are diligent and hard-working—but they can be anxious perfectionists. Type B’s are happy-go-lucky dreamers, but they can be self-centered. According to Korea Biomedical Review, O types are well-rounded and extroverted but can be stubborn, and AB types are eccentric individualists.
Like personality categorization, blood type personality lends itself to being an identifier that can give romantic matches a quick understanding of exactly who you are—just like the zodiac can, for better or worse (sorry, Geminis). The Korea Herald further explains that a match between a type A woman and a type B man is thought to be impossible (or, at least ill-suited)—a 2005 Korea rom-com, My Boyfriend is Type B, even explored this idea, to the chagrin of many type Bs in real life. The idea of blood type has come up frequently in Korean pop culture in the 21st century: in the romantic k-drama Crash Landing on You, the matched O blood types of a couple makes their love story seem especially fated, and in the k-drama Startup, and eventually rejected love interest is teased that, due to his perfectionist, competitive nature, he must be type A. (He is).
Although, generally speaking, blood type personality is as lighthearted a topic as whatever the moon’s doing to your astrological sign, it stems from a far more discriminatory belief and inhuman research. Korea Biomedical Review explains that the pseudoscience originated from research done in Nazi Germany, which sought to pinpoint the superior blood type. It was adopted by a Japanese psychologist, picked up in popularity in the later 20th century, and eventually arrived in Korea, where it was embraced by younger generations. It’s still a big consideration for many: The Korea Herald mentions that a 2017 poll by Gallup Korea showed that a considerable 58-percent of the population still believes that blood type is related to personality. In 2014, a Japanese study found no scientific correlation between the two.
This form of categorization likely persists because humans seem to love identifiers—and especially in the age of the internet, we’ve gripped onto them perhaps even more strongly than ever before (hence why it’s not uncommon to see a Hinge profile that notes both Myers-Briggs type and astrological sign. Maybe even love language, too). At worst, it’s a form of discrimination that can put some people at a disadvantage in terms of perception, through no fault of their own. And at best, it's yet another way we try to understand: Who are you?