Both parents are heterozygous for Tay-Sachs disease (an autosomal recessive disorder). Three children in a row were born with Tay-Sachs disease. What is the chance that a fourth child will have Tay-Sachs disease?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

Question

Quizplus · Accepted Answer

The chance of a child inheriting Tay-Sachs disease when both parents are heterozygous is 25%, regardless of the outcomes of previous pregnancies.

Both Parents Are Heterozygous for Tay-Sachs Disease (An Autosomal Recessive