In humans, brown eye color dominates over blue, and the ability to control the right hand

In humans, brown eye color dominates over blue, and the ability to control the right hand over left-handedness. Moreover, the gene for both traits is located on different chromosomes. Both parents are brown-eyed right-handed people are heterozygous for both traits. What is the probability of birth: a) brown-eyed right-handed) brown-eyed left-handed) blue-eyed left-hander.

Let the gene for the development of the brown iris be B, then the gene responsible for the development of the blue iris is b.

Let the left hemispheric lateralization, which determines the dominant position of the right hand, be C, then gene c will be responsible for the right hemispheric lateralization.

Parents, according to the condition of the problem, have brown eyes and a right hand as dominant; in addition, it is known that they are heterozygotes for the named traits – BbCc. Both of them form sex cells of the following types: BC, bc, Bc and bC.

Possible offspring of such a pair:

brown-eyed right-handers (ВВСС, 4 ВbCs, 2 ВbCC, 2 ВВСс);

blue-eyed left-handed children (bbcc);

blue-eyed right-handers (2 bbСс, bbСС);

brown-eyed left-handers (2 Bbcc, Bbcc).

The probability of giving birth to a brown-eyed right-hander: (9 * 100) / 16 = 56.25%.

The probability of giving birth to a brown-eyed left-hander: (3 * 100) / 16 = 18.75%.

The probability of the birth of a blue-eyed left-hander (1 * 100) / 16 = 6.25%.