What should the practical nurse tell Ms. Hudson about predicting the eye color of her twins, given the mother has brown eyes and the father has blue eyes?

What should the practical nurse tell Ms. Hudson about predicting the eye color of her twins, given the mother has brown eyes and the father has blue eyes?

• A. Eye color is genetically random, and it is not possible to predict.
• B. Both babies will likely have blue eyes.
• C. One baby will have brown eyes, and the other will have blue eyes.
• D. Both babies will most likely, but not certainly, have brown eyes.

Answer: (D)

Brown eyes are usually dominant over blue in this simplified inheritance model. The mother has brown eyes and could be BB or Bb, while the father has blue eyes and is bb. Each baby inherits one allele from each parent. If the mother is BB, every baby would be brown. If the mother is Bb, each baby has a 50% chance of brown and a 50% chance of blue. Since we don’t know the mother’s exact genotype, brown eyes are more likely overall for the twins, but it isn’t guaranteed. That’s why the best guidance is that both babies will most likely, but not certainly, have brown eyes.

Brown eyes are usually dominant over blue in this simplified inheritance model. The mother has brown eyes and could be BB or Bb, while the father has blue eyes and is bb. Each baby inherits one allele from each parent. If the mother is BB, every baby would be brown. If the mother is Bb, each baby has a 50% chance of brown and a 50% chance of blue. Since we don’t know the mother’s exact genotype, brown eyes are more likely overall for the twins, but it isn’t guaranteed. That’s why the best guidance is that both babies will most likely, but not certainly, have brown eyes.