Interesting Tidbits: In the Blood

Though astrology and Chinese zodiac is pretty much known all over the world, Japan has its own form of divination - in blood. In just about the same way astrology claims to be able to tell a person's personality through the stars they were born under, it's a rather commonplace belief in Japan that you can read personality through blood. Hence why Japanese Facebook will ask you for your blood type!
 Does it hold together? Have a look for yourself. Here's what is said about the four major blood groups (I guess all you HH guys will have to figure it out on your own.)

A BLOOD GROUP:

Best traits	Earnest, creative, sensible, reserved, patient, responsible
Worst traits	Fastidious, over-earnest, stubborn, tense

B BLOOD GROUP:

Best traits	Passionate, active, doer, creative, wild, strong
Worst traits	Selfish, irresponsible, unforgiving, erratic

AB BLOOD GROUP

Best traits	Cool, controlled, rational, sociable, adaptable
Worst traits	Critical, indecisive, forgetful, irresponsible, "split personality"

O BLOOD GROUP

Best traits	Confident, self-determined, optimistic, strong-willed, intuitive
Worst traits	Self-centered, cold, doubtful, unpredictable, "workaholic"

 
Apparently, Rh (whether you're A+ or A-, for example,) doesn't affect your reading.
All in all, I can see how it would make sense that something as hereditary as the blood running through your veins can affect personality more than anything else, but I personally find it a little odd to state that there are only 4 types of people in the world. OR maybe that's just me being earnest and stubborn! A penny for your thoughts!