What characterizes a polygenic trait?

A polygenic trait is characterized by being controlled by multiple genes, meaning that several different genes contribute to the phenotype (observable characteristics). Each gene involved may have multiple alleles, and these alleles can interact in various ways, leading to a range of possible phenotypes. For example, traits such as height, skin color, and intelligence are influenced by many genes, making them polygenic in nature.

This multi-gene interaction results in a continuous variation among individuals rather than distinct categories. This is a key feature of polygenic traits, distinguishing them from traits that are determined by a single gene, which would show a more discrete distribution. Additionally, while environmental factors can influence polygenic traits, they are not the sole determinants of their expression. Finally, complete dominance, where one allele completely masks the effect of another, is not fundamentally characteristic of polygenic traits, as these traits can exhibit a variety of inheritance patterns, including incomplete dominance and co-dominance among the multiple genes involved.