A brown-eyed right-hander marries a blue-eyed right-hander. The first child has blue eyes and turns out to be left-handed.
A brown-eyed right-hander marries a blue-eyed right-hander. The first child has blue eyes and turns out to be left-handed. What are the genotypes of the parents, and what might be the phenotypically further offspring of this pair?
Let’s designate brown-eyed as “A”, right-handedness as “B”, then blue-eyed will be designated “a”, left-handedness – “b”.
A left-hander with blue eyes, as having both recessive traits, will have the aavv genotype. Homozygosity is a condition under which a recessive trait acquires the ability to be realized in a phenotype.
Then the mother is a carrier of the aaBb genotype, because one of the recessive genes in a pair of her son is inherited from her. Possible mother’s eggs: aB and ab.
A father, a brown-eyed right-hander, can be the parent of a blue-eyed left-hander if he has externally recessive genes in his genotype. Consequently, the father’s genotype is AaBb. Possible spermatozoa of the father: AB, ab, Ab and ab.
In the offspring of this pair, the following options are possible:
brown-eyed right-handed children (AABB, AaBb);
brown-eyed left-handed children (Aabb);
blue-eyed right-handed children (aaBb, aaBB);
blue-eyed left-handed children (aabb).