In fact, when I began working with children with autism, I quickly saw that 8 out of 10 of them are blood type "A".
An "A" myself, this told me a lot about the little bodies they were in and what their special needs were.
Today, it is even more common to hear the Japanese ask your blood type than it is for Americans to ask your astrological sign.
To most Japanese both biology and genetics have a role in determining personality.
While there is not a lot of "hard science" to date on blood type, it makes a lot of "common sense" to look further into this theory.