Question

Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two

parents with normal pigmentation have an albino child. What is the probability that their next three
children will be albino?
A) 3/4
B) 1/4
C) 0%
D) 1/8
E) 1/64

Answer 1

The probability that two heterozygous parents for the recessive albinism gene will have three albino children consecutively is 1/64.

Step-by-step explanation:

Albinism is the result of an autosomal recessive gene, so when two parents with normal pigmentation (who must both be heterozygous carriers of the recessive gene) have an albino child, the parent's genotypes are both Aa. Whenever a couple that has the genotypic form Aa has a child, there is a 1 in 4 chance that the child will be albino (aa). The probability of them having three albino children in a row is the product of three independent events of 1/4 each.

The calculation is as follows: (1/4) x (1/4) x (1/4) = 1/64. Therefore, the probability that the next three children will be albino is 1/64, which corresponds with option E.