Most human traits are determined by multiple pairs of genes, many with alternate codes, accounting for some dissimilar forms that occur with certain genetic disorders. What type of inheritance involves multiple genes at different loci, with each gene exerting a small additive effect in determining a trait?

Polygenetic inheritance

Explanation

Polygenetic inheritance also called Multifactorial inheritance it occurs when a single characteristic is controlled by more than two genes.

An example is the human skin pigmentation which is determined by the amount of melanin it contains.

Melanin production involves at least four genes. A combination of of melanin producing allele determines the degree of pigmentation.

This shows each gene has exerted a small addictive effect in determining the trait.