A woman with brown eyes, which has two brothers, marries a man with brown eyes, which has a brother and two sisters, and produces a boy with brown eyes. When their son marries a woman with blue eyes, they have a girl with blue eyes. All of the boy's aunts and uncles have brown eyes, as do his grandparents. However, his mother, the little girl's grandmother, has an uncle with blue eyes. Trace the family history of eye color and determine how the little girl could have blue eyes.