The following question refers to the pedigree chart in the figure for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.

What is the likelihood that the offspring of IV-3 and IV-4 will have the trait?
A) 0%
B) 50%
C) 75%
D) 100%

Question

The following question refers to the pedigree chart in the figure for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.

What is the likelihood that the offspring of IV-3 and IV-4 will have the trait?
A) 0% 
B) 50% 
C) 75% 
D) 100%

Quizplus · Accepted Answer

IV-3 and IV-4 are both carriers of the trait, as indicated by their half-filled shapes. This means that there is a 50% chance that they will pass the trait to their offspring. However, it is also possible that they could both pass on the dominant normal allele (not shaded in the diagram) to their offspring, in which case the offspring would not have the trait. Therefore, the likelihood of their offspring having the trait is 50%.

The Following Question Refers to the Pedigree Chart in the Figure