My 10 month old german shepard fears father in law

Question
I have a 10 month old female german shepard, she is extremely friendly with everyone kids, adults, other dogs, cats with the exception of my father in law.  He works as a meat cutter at a meat packaging plant.  I don't know if it the smell or what but she runs and hides right when she comes near him or his house.  He gave us a pair of gloves to take camping for handling wood and she was then afraid of us while we had them on.  We burned the gloves and she was fine.  He did tease her a bit when she was a pup but only with toys.  I have tried to get him to just ignore her but he doesn't listen.  I am a dog groomer and have never before witnessed a dog react this dramatically to one person.  He has never been alone with her to abuse her in any way.

Answer
Take command of this situation before you have children and this man interferes with your family.

This is YOUR dog and your home.  She has a reason to fear him, whatever it is (something we will never know) and you must respect this response because rehabilitating it appears to be close to impossible (as the man won't likely cooperate and might make the situation even worse.)  Put the dog in a locked room when he visits and absolutely insist that he leave her alone.  This is a grown man; if his feelings are hurt, let him deal with it.  Expect your partner (whose father he is) to stand with you on this 100%.