A brown-eyed deaf left-hander marries a blue-eyed right-hander with normal hearing.

A brown-eyed deaf left-hander marries a blue-eyed right-hander with normal hearing. A left-handed daughter, blue-eyed and deaf, was born. What are the genotypes of all family members? What is the likelihood of having a brown-eyed baby with normal hearing and right-handedness? If normal hearing and right-handedness are dominant signs.

It is known that the brown-eyed gene is dominant in relation to the blue-eyed gene, let’s designate it A, then the blue-eyed gene will be a.

The dominant gene is responsible for the development of normal hearing, let’s designate it B, then the deafness gene will be b.

Right-handedness, which is also a dominant feature, will be denoted C, then left-handedness will be c.

The blue-eyed deaf left-handed daughter will be aavwss, since homozygosity for all three traits under consideration is a necessary condition for their phenotypic realization, because they are recessive.

The parents of such a child must either themselves possess a recessive homozygous genotype for each of the traits, or, at least, carry unmanifest recessive genes in their genotypes.

Consequently, the brown-eyed deaf left-hander, the father of the child, will be Aabbcc, he will produce spermatozoa Abc and abc.

The blue-eyed right-hander with normal hearing, the mother of the child, will be aaBbCc, her eggs will be abc, aBc and abC.

Possible options for the offspring of this married couple:

brown-eyed deaf left-handed children (Aabbcc);

brown-eyed left-handers with normal hearing (AaBbcc);

brown-eyed deaf right-handers (АаbbСс);

blue-eyed deaf left-handers (aabbcc);

blue-eyed normally hearing left-handers (aaBbcc);

blue-eyed deaf right-handers (ааbbСс).

As we can see, a brown-eyed right-hander with normal hearing cannot be born to this couple.