Many Japanese people like to think that blood type can predict personality, with type A blood being more fastidious, type B being more wild, type O being more unmotivated, and type AB being more mentally unstable.
There is very little truth in that, as many type O people are more organized than some type A people.
Or is there? in a recent study, type AB blood has a higher level of a certain chemical that is related to greater risk for high blood pressure and worse cardiovascular health, on average. This also includes loss of cognitive ability: trouble learning and memory loss. Type O blood had the lowest average risk of developing similar problems.
So some sayings may have some obscure truth to them, after all.
Source: Can your blood type affect your memory? – PsyPost.
Image: Jamie雪宁 😛