How is your mind affected by your blood type?

It is not.: Blood type is determined by the presence or absence of different proteins on the surface of your red blood cells. These proteins are part of how the body recognizes self from not-self. They are important for blood transfusion, organ transplants, and occasionally in pregnancy if, but otherwise have little effect on your health.

It is not: There's a series of phony books from the 1990's claiming that blood type affects mind and body in a huge number ways, without any evidence whatever. They were simply money-makers. Ignore anything you may hear about this stuff. Best wishes.