One of a number of genes, each of small effect, which together act to determine the phenotype of a quantitative trait. The result is continuous variation in the trait and a seemingly non-Mendelian mode of inheritance.
A polygene, multiple factor, or quantitative gene is a group of nonallelic genes that together influence a phenotypic trait. The loci or identities of the nonallelic genes are frequently unknown to biologists, even though they are known to exist. The genes that contribute to type 2 diabetes are thought to be mostly polygenes.