Answer:
% Normal chin (NN) - 25%
% Normal chin (Nn) - 50%
Explanation:
Create a punnett square using Nn and Nn. Since both mom and dad have a dominant trait, but carries that recessive trait, it is considered "Nn".
N n x N n = NN, Nn, Nn, nn
% Normal chin (NN) - 25%
% Normal chin (Nn) - 50%
% Abnormal chin (nn) - 25%
