My granddaughter has a child born with blue eyes. The father and mother both have brown eyes as well as grandparents on both sides. How rare is it for my great granddaughter to have blue eyes? My eyes are hazel, but I am the great grandmother.

Well in general brown eyes are the dominant trait but blue eyes are actually a mutation. One of the factors you have to account for is what will be the father's eye color? Also if having blue eyes is common in his family blood line or not.

Hoped this helped!