What best describes polygenic inheritance?

• A. The influence of a single gene on a trait
• B. The inheritance pattern governed by environmental factors
• C. Multiple genes affecting a trait leading to continuous variation
• D. Inheritance not influenced by genetic variations

Answer: (C)

Polygenic inheritance best describes the phenomenon where multiple genes contribute to a single trait, resulting in a wide range of possible phenotypes. This is particularly evident in traits that show continuous variation, such as height, skin color, or intelligence, where numerous gene interactions lead to subtle differences rather than distinct categories.

In polygenic traits, the cumulative effect of many genes—each contributing a small amount to the overall effect—results in a gradient of phenotypic expression rather than a clear-cut Mendelian ratio. This concept contrasts with the idea of monogenic inheritance, where a single gene determines a trait. Environmental factors can influence the expression of polygenic traits, but the defining characteristic is that multiple genes are involved in shaping the phenotype. Thus, the essence of polygenic inheritance lies in the complex interplay between different genes, creating a continuous spectrum of variation rather than categorical outcomes.