relationship that occurs when two alleles are both expressed in the heterozygote, and both phenotypes are seen simultaneously. Multiple alleles refers to the situation when there are more than 2 common alleles of a particular gene. Blood groups in humans is a classic example. The ABO blood group proteins are important in determining blood type in humans, and this is determined by different alleles of the one locus. Schizotypy Schizotypy is an example of a psychological phenotypic trait found in schizophrenia-spectrum disorders. Studies have shown that gender and age influences the expression of schizotypal traits. For instance, certain schizotypal traits may develop further during adolescence, whereas others stay the same during this period. See also Allometric engineering of traits Character displacement Phene Race (biology) Skill Eye color Citations References Lawrence, Eleanor (2005) Henderson's Dictionary of Biology. Pearson, Prentice Hall. External links Cartesian Coordinate Classification of Body Type and Personality Classical genetics