You should not have to start over, but I would advise you to back up your savegame files before you do anything else (as a precaution).

I suspected that you actually had 30 generations, which is why I asked about your game version. There is a bug in some versions of Virtual Families (that you can read about here) that causes what you described. Fortunately, that bug was fixed, and you can see how to get the updated version in Arthur's announcement post. Installing 1.00.09 should take care of the problems you're having, as you can see from this discussion.