In humans, the gene that causes one of the background of hereditary deaf-mute is recessive

In humans, the gene that causes one of the background of hereditary deaf-mute is recessive, in relation to the gene for normal hearing, a deaf-mute child will be born from the marriage of a deaf-mute woman with a normal man, determine the genotypes of all family members.

Let’s designate the gene that leads to deaf-mute as g, and the gene that causes normal hearing as G.

A deaf-mute woman has the gg genotype, because only homozygosity for the deaf-mute gene can lead to the manifestation of pathology. This woman produces the same type of germ cells g, that is, she is able to transmit only a pathological gene to her offspring.

A deaf and dumb child, like a mother – gg. He receives the second gene g from the father, therefore, the normally hearing father is heterozygous. We write it as Gg, and the sperm produced by it are g and G.

This couple has a 50% chance of having a deaf-mute child (gg). The rest of the children will have normal hearing (Gg) – 50%.