In humans, brown eye color dominates over blue, and right-handedness over left-handedness.

In humans, brown eye color dominates over blue, and right-handedness over left-handedness. A brown-eyed right-handed woman, whose mother was left-handed and whose father was blue-eyed, married a brown-eyed right-hander. They had a blue-eyed left-hander. Questions: a) What is the probability of birth of right-handers, b) … left-handers c) … brown-eyed left-handers?

Given:

A – right-handed;
a – left-handed;
B – brown;
b – blue;

Decision:
P (mother) Aabb x (father) AaBb;
Gametes (G): Ab, ab – AB, aB, ab, Ab;

F1: AABb (right-handed, brown), AaBb (right-handed, brown), Aabb (right-handed, blue), AAbb (right-handed, blue), AaBb (right-handed, brown), aaBb (left-handed, brown), aabbb (left-handed, blue) , Aabb (right-handed, blue).

Answer:

1. The probability of birth of right-handers is 75%.
2. The probability of birth of left-handers is 25%.
3. The probability of giving birth to a brown-eyed left-hander is 12.5%.