Japanese strange habit

Before exams, I always become eager about something irrelevant to studying...
I'm managing to pass them at last, maybe...

Japanese have a strange habit.
They often judge people and their characters with their blood type.
Every blood type has different features, such as...

(positive)
People whose bloodtype is A are precise, self-possessed and earnest.
People who has blood type B have a lot of interests, are emotional. And they're optimists.
O; they are placid and good at socializing.
AB; they are rational and something of a genius.

(negative)
A; they are nervous and have a frosty personality.
B; they are persons of moods and don't worry about other people.
O; they're rough.
AB; they're strange.

Are these ideas right?