A secretor is defined as a person who secretes his or her blood type antigens into body fluids and secretions like the saliva in your mouth, the mucus in your digestive tract and respiratory cavities, etc.  A non-secretor on the other hand puts little to none of their blood type into these same fluids. As a general rule, in the US about 20% of the population is non-secretor. Listen to Peter and his special guest Dr. Tara Nayak dig deeper.