Here's the problem:
red hair is a recessive trait; non-red hair is dominant. suppose two people with brown
(non-red) hair have a red-haired child. a) what are the genotypes of each parent (use hh, hh, or hh)? b) what was the
probability of them having a red-haired child? c) what are all the possible genotypes of their children?

i already understand the answers to all of these. what i need with is this part:

what is the % probability of the couple having 3 children in a row with red hair?

how do i begin to calculate this? i suck at probability lol