A woman who is a carrier for haemophilia (XᴴXʰ) has children with an unaffected man (XᴴY). What is the probability that a daughter is a carrier?
Answer and explanation
Correct answer: B. 50%
- Step 1: Daughters get Xᴴ from the father and either Xᴴ or Xʰ from the mother, so half are carriers.
Answer
50%.
Why not the others: 0%: half of the daughters inherit Xʰ from the mother. 25%: 25% is the chance of any child (son or daughter) being a carrier daughter; among daughters it is higher. 100%: only half of the daughters inherit the Xʰ allele.
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