In humans, there are two forms of deaf-dumbness, which are determined by recessive autosomal unlinked genes

In humans, there are two forms of deaf-dumbness, which are determined by recessive autosomal unlinked genes. What is the probability of having children deaf and dumb in a family where both parents suffer from the same form of deaf and dumb and are heterozygous for the other form of deaf and dumb?

Let us designate the gene that determines the development of deaf-dumbness of type I as in, then the corresponding gene of normal hearing will be B. The gene responsible for the development of deaf-dumbness of type II will be denoted with, the corresponding gene for normal hearing is C.

Both parents, according to the condition of the problem, suffer from deaf-dumbness of one type, according to the second they are heterozygous. Let’s write them as bbСс. Both of them produce two types of germ cells: bC and bc.

Possible options for the offspring of such a married couple:

children with type I deaf-dumbness (bbCC, bbCc) – 75%;

children with combined type I and II deafness (bbcc) – 25%.

Answer: 100%