In humans, the brown-eye gene dominates over blue eyes, and the ability to dominate the right hand

In humans, the brown-eye gene dominates over blue eyes, and the ability to dominate the right hand over left-handedness. Genes are not linked. A blue-eyed right-hander married a brown-eyed right-hander. They had two children: a brown-eyed left-hander and a blue-eyed right-hander. Determine the likelihood of the birth of blue-eyed children in this family, wielding mainly the left hand.

A – brown eye color, a – blue eye color, B – right-handed, b – left-handed. If a blue-eyed right-handed man and a brown-eyed right-handed woman had a brown-eyed left-hander and a blue-eyed right-hander, then they are heterozygous for these characteristics.

Parents: aaBb × AaBb

Gametes: aB ab AB Ab

aB ab

Prospective offspring: AaBB brown-eyed child, right-handed, AaBb brown-eyed child, right-handed, aaBB blue-eyed right-hander, aaBb blue-eyed right-hander, AaBb brown-eyed right-hander, Aabb brown-eyed left-hander, aaBb blue-eyed right-hander, aabb blue-eyed left-hander. The probability of the birth of blue-eyed children in this family, possessing mainly the left hand, is 12.5%.