Let's say that the gene for brown eyes is dominant,and the gene for blue eyes is recessive.Mary and Joe both have brown eyes,but their daughter has blue eyes.Which of the following statements is true?
A) Mary and Joe are both homozygous for eye colour.
B) One of these parents is probably not biologically related to the child.
C) Mary and Joe are both heterozygous for eye colour.
D) There is no way to determine anything about your parents based on this information.

Question

Quizplus · Accepted Answer

For Mary and Joe's daughter to have blue eyes, both Mary and Joe must have the recessive gene for blue eyes. This means that both Mary and Joe must be carriers of the blue eye gene, therefore heterozygous for eye color. It is possible for two people with brown eyes to have a child with blue eyes if they are both carriers of the recessive gene. Therefore, choice A and B can be ruled out. D is also incorrect since we were able to determine that Mary and Joe are both heterozygous for eye color based on the information given.

Let's Say That the Gene for Brown Eyes Is Dominant,and