Don’t be so sure. As long as they don’t have a “BB” Brown rather than a “Bb” Brown, and the other parent has “bb” Blue, there’s a 50% chance their eyes will be blue. My parents were both “Bb” Browns and I came out a “bb” Blue, which is a 25% or less chance.
80% of the human population has brown eyes.
Blue eyes are recessive so for a child to have them, both parents must have blue eyes.
My mom had blue eyes my dad had green eyes so I came out brown!