Respuesta :
The likelihood that the fourth generation will be impacted by the disease is 25% such that the child is homozygous recessive.
What is meant by heterozygous?
Each pair of chromosomes in a diploid animal contains two alleles, one from the father and one from the mother, for each gene that determines a trait. A gene can exist in two or more different forms, known as alleles, and they can all be present at the same location, or locus, on a chromosome. The term "heterozygous" describes the presence of several alleles for a given trait. You have a heterozygous genotype for that gene if the two versions differ from one another. Which qualities are expressed depends on how the two alleles are related.
If both parents are carriers of the recessive allele for a disorder, all of their children will face the following odds of inheriting it:
25% chance of having the recessive disorder
50% chance of being a healthy carrier
25% chance of being healthy and not have the recessive allele at all.
Let's say you and your partner are both carriers for cystic fibrosis, an illness that is genetically inherited but is very painful. Of course, you are concerned about how healthy and typical your children will be. Let's define "A" for this example as the dominant allele that is normal and "a" as the recessive aberrant allele that causes cystic fibrosis. You and your partner are heterozygous since you are both carriers (Aa). Only people who are homozygous recessive are affected by this condition (aa). According to the Punnett square, you have a 25% chance of having a healthy homozygous (AA) child, a 50% chance of having a healthy heterozygous (Aa) carrier child, just like you and your partner, and a 25% risk of having a child with a genetic disorder.
To learn more about pedigree from the given link :
https://brainly.com/question/20326943
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