Two Bb parents have two children. What is the probability that both children have the genotype bb?
Answer and explanation
Correct answer: B. 1 in 16
- Step 1: Chance of bb for one child is 1/4.
- Step 2: Births are independent, so multiply: 1/4 × 1/4 = 1/16.
Answer
1 in 16.
Why not the others: 1 in 8: this multiplies 1/4 by 1/2. 1 in 4: this is the chance for one child. 1 in 2: this is not produced by the cross.
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