Cumulative gene, also known as polygenes or quantitative trait loci (QTL), refers to a group of genes that contribute to a particular physical or behavioral trait. These genes do not exhibit a clear Mendelian pattern of inheritance and their effects are additive, meaning that the more copies of the genes present, the stronger the effect on the trait. Synonyms for cumulative gene include complex genes, polygenic traits, multifactorial traits, and multiple genes contributing to a single trait. Understanding the role of cumulative genes in various traits can help researchers better understand the genetic basis of diseases and other complex traits in humans and other organisms.