What is your blood type?

I am asked this by Korean children.  There is the "ask the new teacher from America question" time at the beginning of the semester.  Some little kid pops up his or her hand and says, "teacher, what it your blood type?"

The first time I was quite surprised.

My blood type is A.

Koreans (not all) think that your blood type determines your personality.

Hitler had type A blood.  So does Britney Spears.  How lucky am I?

People with type A blood are supposed to be: calm, patient, sensitive, responsible, overcautious, stubborn, unable to relax.  Obviously they hit the mark with this blood type personality thing (not!  I do not think I have ever been labeled calm)

There is also a theory about which blood types should marry other blood types.  But I do not remember anything about it.