Answer:
Depends
Explanation:
It depends if the genotypes are hetero.zygous or resessive/dominant homo.zygous. Being colorblind could be represented by a resessive genotype like, bb. if their son/daughter has Bb or bb or their son/daughter in law has a resessive trait then having a color blind grandchild maybe possible. The colorblind grandson has parents that both have at least 1 resessive trait, then the grandson could not be colorblind.
