What type of inheritance involves more than two alleles for a trait?

The concept of multiple alleles refers to a situation in genetics where a gene has more than two alternative forms (alleles) present within a population. This means that instead of the traditional two alleles (one from each parent), there can be three or more different alleles for a particular trait.

A classic example of multiple alleles in humans is the ABO blood group system, where the presence of alleles A, B, and O determines an individual's blood type. This results in four possible phenotypes (A, B, AB, and O) stemming from the interactions of these three alleles.

This genetic phenomenon is essential for understanding complex traits and variations within a species, as it provides a broader range of potential genetic combinations than just simple dominance or recessiveness associated with Mendelian inheritance.

In contrast, polygenic inheritance involves multiple genes influencing a single trait, while incomplete dominance refers to a blending of traits rather than the presence of multiple alleles. Incomplete segregation is not a recognized term in this context, which further highlights the specificity of multiple alleles to this question.