Many people are Rh-positive than Rh-negative, therefore it is considered a rare type of blood. Before we go any further, it is important to know what we mean when we talk of the Rh-negative blood type and their personality trait. Blood Groups and Where Rh-Negative Blood Type Fits in.In 1954, when Harrison turned 18 and started giving blood, it was quickly discovered that his blood contained a rare, very valuable lifesaving antibody that could be used to treat Rhesus disease.