Following from the postings related to organ transplants and animal essence, I was reminded that in Japan there is a popular belief that personality and compatibility is determined by which blood group (ABO) you have. This wacky theory apparently surfaced in 1927 following the publication of a Japanese paper, “The Study of Temperament Through Blood Type” which attempted to explain personality differences in terms of blood group. In another study, the author, Takeji Furukawa, wanted to “penetrate the essence of the racial traits of the Taiwanese, who recently revolted and behaved so cruelly.” The essence theory really got going in the 1970s following the publication of “Understanding Affinity by Blood Type” by Masahiko Nomi. There are of course, real physiological issues about compatibility for blood transfusions but this Japanese theory (which is also found in Korea) claims that it affects personality as well. There are dating agencies that specialize in matching couples on blood, personal ads carry this information and of course, the tabloids offer blood horoscopes.