Is it permissible for a grandmother to lack affection in her heart towards her grandson from her son who is married to a non-Muslim woman?

A Muslim man is not permitted to marry a disbelieving woman unless she is a chaste woman of the People of the Book. He must separate from his wife if she does not believe in Allah. As for the child resulting from your son's marriage to this woman, he is attributed to him as long as he believed their marriage to be permissible. The child is affiliated with his father's lineage, and they inherit from each other by the consensus of Muslims. His lineage is not denied except through li'an (oath of condemnation). Differences in color and resemblance are not a justification for challenging lineage. Therefore, the questioner should consider this child her grandchild.