How is it possible for us to have a genetic disease that your grandparents had/have but our parents never had it

Dominant inheritance means an abnormal gene from one parent can cause disease. This happens even when the matching gene from the other parent is normal. The abnormal gene dominates. This disease can also occur as a new condition in a child when neither parent has the abnormal gene.

Explanation:

answer; /// (c) i do believe that the correct answer is ; an unstated guarantee that goods will be to the consumer's liking;

a)apline.     glad to ! : )