Explain how continuous traits, like human height and skin color, are controlled by multiple alleles of multiple genes.

Continuous traits are determined by total dosage of dominant alleles of all the regulatory gene and exhibit wide variation of phenotype within population.

Explanation:

Continuous traits such as skin color and human height are the polygenic traits and are regulated by multiple alleles of many genes. Each allele of each gene contributes to the phenotype and the effects of all the genes are additive to give a continuous trait.

The phenotype is regulated by the total number of dominant alleles of all the regulatory genes present in an individual.

Human skin color is a polygenic trait and is determined by the regulatory enzymes that determine the production of melanin pigment and its distribution.

Here, the genotype AABBCC having a total of 6 dominant alleles imparts extremely dark skin color to the individual while the genotype "aabbcc" does not have any dominant allele and give extremely light skin color.