A geneticist is studying the inheritance of a trait in humans. She observes that two parents who are both carriers of a specific disease have offspring with a 75% chance of developing the disease. Which of the following is the most likely genotype of the affected offspring?

Core Concept

In a scenario where two parents who are both carriers of a specific disease have offspring with a 75% chance of developing the disease, the most likely genotype of the affected offspring is aa. This is because the offspring are likely to inherit two copies of the recessive allele, one from each parent, resulting in the expression of the disease.