Actually, there was a large study done and there is about a 3% chance of getting it because of familial background. If you have no symptoms I wouldn't worry about it. 3% is pretty low. Consider the age they got it and keep up your annual physicals. Have them check your complete blood counts and unless you have no symptoms I wouldn't worry too much. We all have a hereditary risk to some degree of getting something.
Appendicitis does not spread in families or acquired congenitally.But if your family has got a problem of allergies,like esinophilia,it may run in families and finally lead to esinophilic appendicitis,which is a rare condition.
Considering you have normal history from background,I do not think that yu are prone for acquiring appendicitis.Talk to your Doctor if you have any strange symptoms of abdomen or any other and get evaluated.