Which genetic phenomenon results in a blend of traits where each gene contributes a small effect?

Polygenic inheritance refers to the genetic phenomenon where multiple genes, each contributing a small effect, influence a single trait. This contrasts with traits determined by a single gene, where the expression is more straightforward and can often be categorized into discrete variations, such as those seen in Mendelian inheritance.

In polygenic inheritance, the overall phenotype results from the cumulative effects of many genes, which can lead to a continuous range of phenotypes. For instance, traits like height, skin color, and intelligence are influenced by the interactions of several genes, leading to the wide variation observed in these characteristics among individuals.

This mechanism underlies complex traits because it allows for a blend of traits rather than a clear-cut expression. The interactions among different alleles can produce an array of phenotypes that are quantitatively measurable, rather than simply categorically defined.