If green eyes are dominant and designated as "G" and gray eyes are recessive and designated as "g," probability would predict that if a couple each with a "Gg" eye color genotype had four children, _____ would have gray eyes.

Question

Quizplus · Accepted Answer

If both parents have the genotype "Gg", they each have one green eye allele and one gray eye allele. When they have offspring, they can pass on either their green or gray allele to each child. The Punnett square for the cross would be:

|   | G  | g  |
|---|---|---|
| G | GG | Gg |
| g | Gg | gg |

There are four possible genotypes for their children: GG, Gg, Gg, and gg. Only the last genotype (gray eyes) would result in a child with gray eyes, so the probability of any individual child having gray eyes is 1/4 or 25%. For four children, we would expect one of them to have gray eyes based on probability.

If Green Eyes Are Dominant and Designated as "G" and Gray