Why is it said that AB positive or negative blood type people are aliens from another planet?
I guess because some people who talk about blood type don’t know anything about genetics. There are two major blood antigen systems: *** and Rhesus factor. A and B are codominant. Some people pass on genes that don’t carry either of these, so it’s referred to as O. If you have AO or AA, your blood type is A. BO or BB, blood type B. AB, blood type AB. OO, blood type O. In addition, the Rhesus factor is dominant, and its presence is referred to as Rh+ or just a + after the *** group blood type. AB+ is called the “universal recipient” because such a person has all antigens (A, B, and Rh+), so no donated blood could have an antigen that the body woudl reject. AB+ and AB- are rare blood types only because of genetic frequencies; Rh-, for example, occurs only in about 16% of caucasians, and is rarer in every other population group except for Basques, in which it occurs at a rate of 35%.
