In a disease that is associated with a single recessive allele, the concordance among dizygotic twins should be ________, assuming both parents are heterozygous carriers.

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In a disease associated with a single recessive allele, with both parents being heterozygous carriers, each child has a 25% chance of inheriting two recessive alleles (one from each parent) and thus expressing the disease. Dizygotic twins are genetically as similar as siblings born at different times, so the concordance rate for the disease among them would also be 25%.

In a Disease That Is Associated with a Single Recessive