Emochromatosis is an inherited disease caused by a recessive allele. if a woman and her husband, who are both carriers, have three children, what is the probability of each of the following?
(a) all three children are of normal phenotype.
(b) one or more of the three children have the disease.
(c) all three children have the disease.
(d) at least one child is phenotypically normal.

(d) At least one child is phenotypically normal.

Explanation:

To be a carrier means that you have the gen but you are not affected by it.

If both parents have that recessive gene, this means, both are heterozygous for that trait.

Let's say this gen is A, for the dominant trait, and "a" if it's recessive.

The mother and the father are Aa.

If you cross them you have Aa x Aa = AA Aa aA aa

This means you have 50% of Aa, carrier children

25% AA, not a carrier or affected by this gen.

25% aa, affected by the gen.