Traits that display continuous phenotypic variation are usually determined by which form of inheritance?

• A. dominant-recessive inheritance
• B. sex-linked inheritance
• C. polygene inheritance
• D. multiple-allele inheritance
• E. incomplete dominance

Answer: (C)

Verified step by step guidance

1. Understand that traits with continuous phenotypic variation, such as height or skin color, do not fall into discrete categories but rather show a range of possibilities.
2. Recognize that dominant-recessive inheritance typically results in discrete phenotypic categories, not continuous variation.
3. Consider sex-linked inheritance, which involves genes located on sex chromosomes, often resulting in distinct phenotypic differences between sexes rather than continuous variation.
4. Evaluate multiple-allele inheritance, where more than two alleles exist for a gene, but this does not necessarily lead to continuous variation.
5. Identify polygene inheritance as the form where multiple genes contribute to a single trait, resulting in continuous phenotypic variation due to the additive effects of many genes.