Question

A normal appearing couple is found to be heterozygous recessive for albinism. Both have the genotype Aa. The gene responsible for albinism is recessive to the normal pigment-producing gene. What are the chances of their children being albino? 3:4 children will be albino. All children will be albino. 1:4 children will be albino.

Answer 1

1:4 children will be albino.
If you make a Punnett square with Aa and Aa, you'll see that the ratios are:
AA:Aa:aa=1:2:1
so the ratio of aa out of the total is 1/(1+2+1)=1/4

Answer 2

1:4 children will be albino.

Step-by-step explanation:

Each parent has the Aa genotype and the genotype of a person with albinism is aa. Therefore, to find out what the chances of the children of this pair are albinos, we must do the Square of Punnett and verify how many times the genotype aa appears.

As you can see in the square below, there are 4 possibility of genotypes for the children of this couple. Of these 4, only 1 genotype shows the aa configuration. So the odds of the couple's children being albinos is 1: 4.