Consider a Trait Determined Entirely by Three Independently Assorting Genes

Multiple Choice

Consider a trait determined entirely by three independently assorting genes with two alleles in which one allele is dominant over the other. As in the wheat seed color example illustrated in Figure 18.4, imagine that each dominant allele contributes one unit to the phenotype of the trait. Individuals with a phenotype of  4 are affected and all other phenotypes are not affected. What is the concordance between same-sex fraternal twins?

A) 11%
B) 21%
C) 34%
D) 45%
E) 57%