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Does blood type affect vocational behavior?

by Andrew D. Carson, Ph.D.

Does blood type affect vocational behavior? In some nations -- for example, Japan -- many people believe that blood type affects personality and vocational success, and people considering marriage might seek to determine compatibility based on blood type (Sabo & Watanabe, 1992; Sullivan, 1995/2000). In that sense, blood type seems to perform a similar function that astrological belief in the power of the Zodiac plays in the West, except that in Japan such views are taken much more seriously; according to Sullivan, "Japan has an obsession with blood types." In the United States, naturopathic medicine often places great store on blood type, and a recent popular treatment of the subject (D'Adamo & Whitney, 1996) described differences between individuals with different blood types in sweeping terms that included vocational differences. Although at first glance the claims that blood type affects vocational behavior may seem absurd, certainly many Japanese and some Americans believe it does, and the empirical evidence (especially the more recent evidence) is sufficiently mixed to give a skeptic pause.

Japanese Views on Vocational Implications

In Japan, where belief that personality is related to blood type is most widespread and has been so for some time (see Sabo & Watanabe, 1992), there have been a number of efforts to apply blood type theory to career development and organizational practices (e.g., marketing and management; see Sullivan, 1995/2000). In World War II, Japan is rumored to have formed battle groups according to blood type (Gunness, 1998). Apparently drawing from the work of Tashitaka Nomi (who has written 30 books on practical implications of blood type), Sullivan provides a table outlining positive traits, negative traits, and appropriate careers for individuals of the four blood types. The career recommendations are provided below:

Type O: Banker, politician, gambler, minister, investment broker, baseball player

Type A: Accountant, librarian, economist, novelist, computer programmer, gossip columnist

Type B: Cook, hairdresser, military leader, talk show host, journalist, golfer

Type AB: Bartender, lawyer, teacher, sales representative, social worker

Western Views: Evolutionary Naturopathy

In the West, the theory that blood type affects basic personality patterns and vocational adjustment rests on inferences regarding the evolutionary psychology of blood type. Type O Blood is assumed to be the "original" type, because it is the most widely distributed across all areas of the world settled by humans; this is why those with Type O blood can be universal donors: as the other types derive from it, alll can receive it, but it cannot receive derivative types. Type O blood is assumed in the theory to have characteristics best suited to the diet of primitive hunter-gathering society, and thrive in a diet heavy in meat, nuts, and fruit but low in grains and milk. D'Adamo and Whitney (1996) assume the Type O has associated personality traits (especially aggressiveness) that are consistent with being a predator at the top of the food chain.

Type A blood is assumed to have developed next, at the time in which agriculture and concentrated human settlements first arose. According to D'Adamo and Whitney, this was between 25,000-15,000 B.C., and somewhere between Asia and the Middle East. D'Adamo and Whitney (1996) speculate that Type A carried with it additional abilities to survive infectious diseases that began to spread more readily in more crowded, agricultural societies. Type A blood is common in the Mediterranean region, and was carried westward into Western Europe by Indo-European peoples. (Japan also has among the highest rates of Type A in East Asia.) The theory assumes that Type A blood is optimized for diets rich in grains but low in meat and dairy products. D'Adamo and Whitney assume the Type A has associated personality traits that are consistent with being a cooperative farmer, needed to get along in croweded communities.

According to D'Adamon and Whitney (1996), Type B developed between 15,000 and 10,000 B.C. in the Himalayan highlands of Asia, where relatively nomadic tribes relied on diets of meat and dairy products collected through herds maintained by the tribes. The theory assumes that Type B blood is able to benefit from diets drawing from meat, dairy products, and agricultural foods. Two major Type B populations developed, the northern (Mongolian) being more nomadic, the souther (Chinese) being more sedentary and agricultural. The Mongolians carried Type B as far as Eastern Europe. D'Adamo and Whitney assume the Type B has the personality traits of an assimilator, able to adapt to new demands.

Type AB blood appears to be a hybrid of A and B, with an optimal diet intermediate between those associated with either type separately. It began to appear around A.D. 900 in Eastern Europe. It remains a relatively rare blood type. Based on the presumed ability of Type AB individuals to process a wide variety of foods, they D'Adamon and Whitney (1996) assume that such individuals will respond with general flexibility to a wide variety of situations and challenges.

Popular theories of blood type also associate personality traits to the four types. For example, Type O individuals are assumed to prefer positions of leadership, agression, and relative independence, while Type A individuals are assumed to prefer positions of cooperation and group harmony. In some ways, theories of personality types associated with each blood type do not appear much different from standard theories of interest types.

Empirical Research and Vocational Implications

There have been a number of studies over the years testing relationships between blood type and personality, and the following brief review is illustrative rather than definitive. I provide this review purely to demonstrate that claims of a relationship between blood type and personality should not be dismissed out of hand. Early published reports (Koga & Kato, 1934; Thompson, 1936) in general found no relation between blood type and personality traits or abilities.

However, more recent research has tended to find some linkages. Rinieris, Stefanis, and Rabavilis (1980), in a large (N=600) study of normal individuals, found greater incidence of obsessional personality traits in blood types A, B, and AB than in type O. In a study of 137 graduate students, Marutham and Prakash (1990) found Type B individuals to have higher neuroticism scores (compared to types O and A) on the Eysenck Personality Inventory; there were no differences on either extraversion or Type A behavior pattern. In a small study of individuals with duodenal ulcers, Neumann, Shoaf, Harvill, Jones, and Edward (1992) reported that Type A individuals had higher trait anger, trait anxiety, and depression compared to Type O individuals on standard measures of personality.

If there are indeed relations between blood type and personality, then it is not impossible that there may also exist differences in typical blood type across occupations, and that some blood types are associated with greater performance or resistance to occupational stress than are others within given occupations. In other words, it may be possible to apply a person-environment fit theory of work using blood type as a person-attribute. However, I recommend a more thorough literature review, followed by empirical research directly testing this notion before engaging in further speculation along these lines.

The blood type diet website (
Blood type and personality (
Comments by a Japanese professor on the dearth of empirical research on personality and blood type by psychologists, although some Japanese psychologists are now beginning to investigate the issue.
Descriptions of Japanese views on blood types, reportedly based on a translation of a handout at an airport in Narita, Japan. Consistent with descriptions of types by D'Adamon and Whitney (1996). A: Farmer, O: Warrior, B: Hunter, and AB: Humanist.
Report: Many Japanese corporations use blood type as the basis for marketing, management, and other business practices. Toshitaka Nomi is the best-known author, having written 30 books on the subject. (Washington Post, via Lancaster Blood Bank).
Excerpt from Book You Are Your Blood Type by Toshitaki Nomi and Alexander Besher (Pocket Books), listing occupations for each type and famous individuals for each type, e.g., Ronald Reagan was Type O, Jimmy Carter was Type A. (Note: PDF File; requires PDF reader from Adobe).
Report: Japanese have used blood types for decisions about dating as well as business practices (BBC).
History of Japanese views on blood types, in relation to Sailor Moon comics.
Classification of Japanese Anime characters by blood types.
Naturopathy: American Association of Naturopathic Physicians.
Quack. The Federal Air Surgeon recommends that pilots not follow quack fad diets such as matching what you eat to your blood type.
R. B. Cattell reportedly reviewed the literature on blood type and personality.
American Red Cross: Blood Donation.
Blood type table for United States, showing percentages for major blood types. 38% is O+, 34% is A+, 9% is B+, 7% is O-, 6% is A-, 3% is AB+, 2% is B-, 1% is AB-. This page also reviews the tests performed on donated blood.


D'Adamo, P. J., & Whitney, C. (1996). Eat right for your type: The individualized diet solution to staying healthy, living longer, and achieving your ideal weight. New York: G. P. Putnam's Sons.

Gunness, C. (1998, June 22). Japanese seek cell-mates. Retrieved December 29, 2001, from

Koga, Y.; Kato, H. (1934). A study of character and temperament. Japanese Journal of Applied Psychology, 2, 382-417.

Marutham, P.; Prakash, Indira J. (1990). A study of the possible relationship of blood types to certain personality variables. Indian Journal of Clinical Psychology, 17(2), 79-81.

Neumann, J. K., Shoaf, F. B., Harvill, L. M., & Jones, E. (1992). Personality traits and blood type in duodenal ulcer patients and healthy controls: Some preliminary results. Medical Psychotherapy: An International Journal, 5, 83-88.

Rinieris, P. M., Stefanis, C. N., Rabavilis, A. D. (1980). Obsessional personality traits and ABO blood types. Neuropsychobiology, 6(3), 128-131.

Sabo, T., & Watanabe, Y. (1992). Psychological studies on blood-typing in Japan. Japanese Psychological Review. 35(2), 234-268.

Sullivan, K. (2000). What's your type? (The title included the word "sign" before type, with sign crossed out). Retrieved December 29, 2001, from (Original work published January 14, 1995, in the Washington Post)

Thompson, G. N., Jr. (1936). Blood type as related to intelligence, emotions, and personality. Journal of Applied Psychology, 20, 785-789.

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