This sort of nervousness is not inherited but learned, because she is scared of a particular type of object. Quite often such fears are connected to the early puppyhood, something similar must have frightened her while she still was very young, or even her mother could have demonstrated examples of such behaviour and she copied it.
She can get over her fears if she encounters these objects not so often. That is the frequency of irritation that causes it, you don't let her to forget about it. Try to keep her away from these objects for a month or so, don't let her see or smell them. Then start slowly, leave the object somewhere in the distance and feed her (she should be hungry) somewhere close by. Make the distance shorter in a week time. Then even shorter and feed just tasty treats, and bring her really close to it when you see that she looks at your hand with treats, not at the object. And after that - start to place treats on the object itself. If the visual image associates with pleasure (treats), normally dogs remain cautious, but lose their fear.
Last edited by David Taggart; 04-14-2014 at 03:28 PM.