More Bloodtype Nonsense
I posted on this topic two days ago. Cathartidae, noting that "Western media outlets are finally catching on to Korea's current obsession of men with blood type-B," has linked to this article from New Zealand: Bad days for South Korea's type-B men.

The article mentions the Japanese origin of the superstition:

In Asia, the subject of linking blood types to personality took off with the 1927 publication of a series of articles by Japanese scholar Takeji Furukawa called The Study of Temperament Through Blood Type.

The concept hit pop culture and mass media in 1971 when Japanese writer Masahiko Nomi expanded upon Furukawa's ideas and wrote Understanding Compatibility from Blood Types.

It also presents the scientific view:

Kim Tae-suk, a doctor in the department of psychiatry at the Catholic University of Korea, said younger Koreans were buying into defining people by blood types because of what they see on TV, movies and in print.

"I can definitively say there is no scientific evidence that links a person's blood type to their character," Kim said.

"Sorry doc," says the blogger from whom this link came, "but you're gonna have to do better than 'there's no scientific evidence' to convince a lot of these chicks otherwise."