The importance of ABO blood types in transfusions is unquestioned. And the associations between blood type and certain diseases are pretty convincing. But some “scientists” have linked blood type to some pretty wacky stuff.
In the first part of the 20th century it seems that there was nothing some researchers didn’t think was connected to blood type. Type A people were said to have the worst hangovers. People with type B blood were supposed to defecate more than other types. Some thought type Os had the best teeth. Among military personnel, people with type O supposedly had weaker characters and type Bs were more impulsive.
Even in more modern times the less-than solid science surrounding blood types continues. Case in point: Eat Right 4 Your Type. This diet advice book suggests that certain ailments are caused by negative reactions between blood cells and sugar-binding proteins found in food. The book recommends specific foods for each blood type to counteract these effects. Critics argue, however, that there is no evidence supporting these ideas (although they admit the diet advice itself is not too bad.)
In Japan, asking “What’s your blood type?” is like asking someone “What’s your sign?” Popular books, magazines and TV programs discuss how blood type contributes to a person’s personality. Write-ups of celebrities, video game characters and even political candidates include blood type so as to help people form their impressions. Matchmaking services and employers even use blood type to help determine compatibility with mates and job assignments.
People with type A blood are supposed to be sensitive perfectionists who can veer towards anxiousness. Type Bs are happy folks who can have eccentric and selfish streaks. Type O people are said to be curious and generous on the positive side, but also sometimes stubborn. People with type AB are thought to be artsy and mysterious, ideas that probably reflect the rareness of this blood type.
The problem is, just as there’s no plausible link between the motions of the stars and a person’s fate, the idea that blood type is linked to a person’s personality, dietary needs or dental fitness is pure fantasy. Our blood types may be different, but there’s no reason to think that explains all of our differences.