According to BellaOnline's Japanese Culture Editor, "The desire to know about blood type, started because of an assertion from the West, which stated that Asians were lower, in the evolutionary chain and that they were more closely related, to animals than other races." Interestingly, that was the start point where Asian countries became deep into the study of blood type.
Finding correlation between blood type and personality traits is one of popular theory in Asia countries, especially in Japan. Even though it has been disproved by Modern Science, some Japanese Scientist such as Furukawa Takeji still took it upon himself to scientifically by matching personality traits to blood type.
It was about 4 years ago in Korea when a movie, "Blood Type B" came out. In the movie, one guy with type B blood was described as a play body and a quick lover with non-responsibility. Because the movie was so popular at that time, many girls almost did not want to go out with a guy with type B blood. However, ironically, the percentage of blood type B is greater than the combination of all other blood types in Korea. I believe that the blood type theory regarding personality traits is almost not credible at all. In addition, the description about each blood type is so general that it could apply to everyone.
Following are the personality traits ascribed to the basic blood types. (If you know yours, try them)
Blood Type A:
Positive Traits: Conservative, introverted, reserved, patient, punctual and inclined to be perfectionists.
Worst Traits: Obsessive, stubborn, self-conscious and uptight.
Referred as 'farmers' in some descriptions, Type A's are said to be considerate of others and loyal to a fault. They can also be secretive and reluctant to share their feelings. Apparently they don't hold their liquor well, either.
Blood Type B:
Type B men have acquired a very negative reputation in Korea and are not considered by many to be good husband material. Often described as 'players', they are perceived as being selfish and mercurial, quick to anger and not terribly reliable. That said, their bad boy image makes them very attractive to women, but not for the long term. (Type B women do not share in this bad rep, for some unexplained reason).
Blood Type AB:
Referred to as 'humanists', Type AB's are said to be controlled more by their heads, than by their hearts. They are rational, good with money, but unpredictable. Although inclined to be distant, they prefer harmony and as such, work well with mediators. Some consider them two-faced, and therefore untrustworthy.
Blood Type O:
Referred to as 'warriors', Type O's are viewed as natural leaders and are often, also, natural athletes. They tend to be outgoing, expressive and passionate, but can also bore others to death with their obsessive drive for success coupled with their absolute convictions that they are winners. This certainty that they will always win explains why they aren't afraid to take risks or gamble. They have a strong physical presence and are unlikely to ever be overlooked.
If you have known and tried them, do you think there is correlation between the personality traits and blood type?