Question

human skin color ranges from very light to dark black, with many distinct skin tones in between. what type of inheritance pattern governs skin color?
o codominance
o incomplete dominance
o multifactorial inheritance
o polygenic inheritance
o x - linked inheritance

Explanation:

• Codominance: Both alleles are expressed equally in the phenotype. For example, in blood types \(AB\), both \(A\) and \(B\) antigens are present. But skin - color is not due to codominance of a single pair of alleles.
• Incomplete dominance: One allele is not completely dominant over the other, resulting in an intermediate phenotype. For example, in snapdragons, a cross between red - flowered and white - flowered plants gives pink - flowered plants. Skin - color is not an intermediate of two extreme phenotypes in a simple one - gene - pair system.
• Multifactorial inheritance: Involves multiple genes and environmental factors. While environment can affect skin color (e.g., sun exposure), the main determinant is genetic and based on multiple genes (not just genes + environment in a non - genetic - basis - dominated way for the core inheritance).
• Polygenic inheritance: Multiple genes contribute to a single trait. Human skin color is determined by at least three genes with six alleles. Each dominant allele (e.g., \(A\), \(B\), \(C\)) adds a small amount of pigment. The more dominant alleles a person has, the darker their skin color. This explains the continuous range of skin tones from very light (e.g., \(aabbcc\)) to very dark (e.g., \(AABBCC\)).
• X - linked inheritance: Traits are determined by genes on the \(X\) chromosome. Skin color is not specifically an \(X\) - linked trait.

Answer:

polygenic inheritance