In a family of brown-eyed right-handed parents, fraternal twins were born, one of whom is brown-eyed left-handed

In a family of brown-eyed right-handed parents, fraternal twins were born, one of whom is brown-eyed left-handed, and the other blue-eyed right-handed. What is the likelihood of having your next child similar to your parents?

As you know, the gene for brown eyes is dominant, let us designate it as K, and the gene for blue eyes as k.

Right-handedness, as a rule, dominates, let us designate the gene that causes it as L. The gene for left-handedness will be designated as l.

Fraternal twins have different genotypes and, in the context of the genetic problem, are equivalent to regular siblings.

Born brothers demonstrate both recessive traits – blue-eyed (kk) and left-handed (ll), which allows us to conclude that the parents are heterozygous for both gene pairs. Only the presence of recessive genes (k and l) in the genotype of both parents leads to the manifestation of recessive traits in the offspring.

Thus, the brown-eyed right-handed parents are KkLl. They produce sex cells of four types: kl, KL, kL, Kl.

The offspring, theoretically possible in a given married couple, are represented by the following options:

right-handed children with brown eyes (KKLL, 2KkLL, 2KKLl, 4KkLl);

left-handed children with brown eyes (2Kkll, KKll);

right-handed children with blue eyes (kkLL, 2kkLl);

left-handed children with blue eyes (kkll).

The probability of having a brown-eyed right-handed child in this couple is 9 out of 16 genotypes, or 56.25%.