The number of phenotypes produced for a given trait depends on how many genes control the trait. Anyhow, The distribution of phenotypes for a typical polygenic trait can often be expressed as a bell-shaped curve.
Many traits are controlled by two or more genes and are, therefore, called polygenic traits. Each gene of a polygenic trait often has two or more alleles. As a result, one polygenic trait can have many possible genotypes and phenotypes.