Skip to main content

Verified by Psychology Today


Stereotyping by Blood Type and Birth Order

Right or wrong, stereotypes linger.

Your blood type can influence your sex life; Japan has condom dispensing machines (see photo) with slot designations for type A, B, O, or AB buyers. Beyond the obvious medical implications, your blood type could also be very significant in determining whom you date and how happy you are-that is if you live in Japan.

In Japan, blood type establishes who you are these days. You are deemed sensitive, anxious, curious, or selfish according to blood type. That's become common (and accepted) Japanese wisdom. Forget that this theory has no scientific basis. Nonetheless, it is the overarching determinant in all things from finding a compatible mate to finding a job.
With its roots in Nazi ideology, The Japan Visitor explained the origins in an article on Japanese culture, "Blood Types - Capillaries hold key to character":

"It all started in 1931 in Japan. Furukawa Takeji (1891-1940) proposed that there was a link between blood type and personality after working in the administration department of a high school and observing the temperamental differences between applicants.

"Furukawa proposed that we humans are simple beings, only requiring two personality types. His report stated that people of blood type A were generally mild tempered and intellectual, while people of blood type B were the opposite, essentially dividing the population into the ‘good' and the ‘bad.'

"In the 1950s, 60s and 70s "Masahiko and Toshitaka Nomi, a father and son team, were responsible for making this a mainstream science, having researched the way in which blood type affects every area of our lives, including relationships, work and leisure."

A recent series of books (one for each of the four blood types) elucidates how blood type indicates personality traits-type A people are sensitive and perfectionists, for example; Type Bs are cheerful and selfish. If you are an O, you're classified as stubborn and ABs are said to be unpredictable. The books topped Japan's bestseller list last year selling more than five million copies. Citizens, including the Prime Minister, are buying into blood-typing as a personality decider.

Is adopting a belief in blood-type branding any more erroneous than deciding someone is conscientious, reticent, bossy or self-centered based on his or her sibling status? Blood type to define your character has its dissenters, but the debate seems far less intense than the one on birth order that has been raging for decades.

Stereotyping by Blood Type and Birth Order

The assignment of labels, be it by blood-type or position in the family, is stereotyping. Birth order proponents have done essentially the same thing as the Japanese-they adhere to theories that pigeonhole and discount individuality and outside influences. In his 1996 book, "Born to Rebel," Frank Sulloway, professor at University of California Berkeley, proposed that the core dimensions of personality were influenced by birth order. Summary points from one of Sulloway's lectures reads: "Firstborns often serve as a surrogate parent and tend to be more closely identified with their parents than are laterborns. As a consequence, firstborns are inclined to defend the status quo, whereas laterborns tend to react against it." Sulloway's research led to tagging first-borns, achievers and ambitious; the youngest, spoiled and attention-seeking and more inclined to risk-taking.

Although Sulloway's theories have been embraced, he has detractors who find holes in his methodology and thinking. The only true way to ascertain that birth order is the overriding contributor to personality characteristics is to study the children within each family, not to compare families, say Sulloway's challengers. Genetics also need to be weighed in the equation as does the family environment and economic status. Consider too, family size and/or dysfunction. Any and all affect development. Since trying to replicate Sulloway's research unsuccessfully and being criticized for some of his conclusions, Sulloway has backed off a bit. A few months ago he told a USA Today reporter, "People love to pigeonhole individuals by birth order. These are modest difference. It's important to understand that there are a lot of exceptions to these generalizations."

Where you stand in the family hierarchy simply doesn't fully explain who you are. Genetics play a role as well; we know that the propensity toward shyness is genetic. In her study of popularity among college students, Alexandra Burt, Assistant Professor of Psychology at Michigan State University found that the most popular students turned out to be the ones with a particular form of a serotonin gene that was also associated with rule-breaking behavior. Burt told me that, "the gene in question could be found in anyone (where at least one biological parent had the gene as well), regardless of birth order." For sake of argument, it is highly probable that Sulloway's risk-taking youngest child, could then be the middle child or oldest if he or she has the required gene. And then there is the debate on I.Q. and birth order, but I'll save that for another time.

Hurrah for the Only Child, But...

In Sulloway's research, the only child fared best. Sulloway reported that only children are the "least predictable subgroup...and tend to be more variable than individuals with siblings." In other words, you can't peg an only child this way or that, but most people still do. The Japanese have coined a phrase, "bura-hara." It means blood type harassment.

Aren't we harassing only children and the youngest child, putting too much pressure on our eldest, for instance, with unsavory birth order labels that just won't go away?

For more: Why Stereotypes Stick: Brain research explains why we believe stereotypes.

Copyright 2009 by Susan Newman

More from Susan Newman Ph.D.
More from Psychology Today