Polygenes

Genes at more than one locus on a chromosome.  Their variations in a particular population can have a combined effect on a discrete phenotypic character.  The individual genes have a small quantitative effect, but together produce a wide range of phenotypical variation.  Also called, multiple factor quantitative genes. 

See Behavior genetics, Gene, Chromosome, Epistatic/epistasis, Phenotype, Polygenic mode of inheritance, Quantitative genetic theory