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 $\ge$ 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%

Question

Quizplus · Accepted Answer

The concordance rate for same-sex fraternal twins is calculated based on the probability that both twins inherit the same combination of alleles that result in the affected phenotype. Since fraternal twins share about 50% of their genes, the probability of both being affected is lower than that of identical twins. Given the genetic model described, the concordance rate is approximately 21%.

Consider a Trait Determined Entirely by Three Independently Assorting Genes ≥\ge≥

Consider a Trait Determined Entirely by Three Independently Assorting Genes $\ge$