Which statement defines polygenic inheritance?

Which statement defines polygenic inheritance?

• A. A polygenic trait is influenced by one gene.
• B. A polygenic trait is influenced by two or more genes.
• C. A polygenic trait is determined solely by environmental factors.
• D. A polygenic trait follows simple Mendelian ratios.

Answer: (B)

Polygenic inheritance involves many genes contributing to a single trait, with each gene adding a small effect. The combined influence of multiple genes produces a continuous range of phenotypes rather than discrete categories. Therefore, a polygenic trait is influenced by two or more genes. This explains why traits like height or skin color show a spectrum of variation rather than simple dominant-recessive patterns. If a trait were controlled by a single gene, it would follow Mendelian ratios and appear in distinct classes; if it were determined solely by the environment, genetics wouldn’t be the organizing factor.

Polygenic inheritance involves many genes contributing to a single trait, with each gene adding a small effect. The combined influence of multiple genes produces a continuous range of phenotypes rather than discrete categories. Therefore, a polygenic trait is influenced by two or more genes. This explains why traits like height or skin color show a spectrum of variation rather than simple dominant-recessive patterns. If a trait were controlled by a single gene, it would follow Mendelian ratios and appear in distinct classes; if it were determined solely by the environment, genetics wouldn’t be the organizing factor.