4 month old shepherd fear aggression

Question
2 weeks ago I adopted a 4 month old anatolian/german shepherd mix. He is healthy, neutered and seems to be very shy and afraid of people.   He is fine with other dogs but has a problem with people. He will come to me but will not let me touch him. He follows me around the house and yard all day and will sit near me but not close enough to touch. If I go to the store and come back he barks and growls at me. He is good with my wife, he acts like a normal dog with her. This past thursday we started a puppy training class at petsmart. He has responded well to the clicker training so far although he would not let the trainer touch him either, and will do the 2 commands he has learned. He also will not let me put the leash on him without force. Is it ok to corner him and force him to have the leash on?. He also behaves badly with my 2 college age sons.

Answer
It sounds like you will need more training than anything at PetSmart can provide.  The problem is not going to fix itself, and it could end up being dangerous as the dog gets older and could possibly bite someone, in defense.  Fear can be related to lack of proper human socialization in early life.  Genetics may predispose a dog to fear behavior, but it can always change and improve.

You did not say exactly what the dog does when you try to touch him.  I assume he backs away, but what if you were to hold his collar while you pet him?  What would he do?

I would like to give you hands-on suggestions, but since I cannot see the dog in person I don't want to tell you to do anything that may make the problem worse or stress him out.  I wouldn't want him to be traumatized or be set back.  Things may have to be taken slowly, and there is no rush.

Petsmart is a retail store, not a professional training facility, so you will only get so much out of it.  They train employees for just 90 hours to be a trainer.  Does the instructor have a dog they have trained to an advanced level off-leash reliability that they use as a demo dog?  I suggest finding an experienced trainer who teaches dogs by physically positioning them, and doesn't rely too much on using food.  For example, to teach a dog sit, the dog is on my left side and I place my hand on his behind, press down and in, as I say "sit", then praise when he does.  Then release, and repeat.  

Clicker training may be ok for some things, but a dog is not working for YOU, he is working for the click and the treat.  There is no working relationship when a treat is held as a bribe in front of their face.  And what do you do if you say "sit" and the dog does not do it?  Repeat your command over and over, until it's meaningless to the dog?  Once a dog understands what the word "sit" means, commands should never be repeated, they should be said once, and followed by either a reward (if dog listens) or a correction and/or to be physically put into a sit.  Rewards are important, but as training progresses, dogs need consequences if they do not listen, too.  

For example, if your 6 year old child was running around a restaurant goofing off, and you told him "sit down" and he heard you but blew you off, kept running around, what would you do?  Would you...
1. Hold up an ice cream sundae and bribe him to sit.
2. Repeat "sit down" 5 times, pleading with the child.
3. Tell him one time, and if he disregards it, go get him and physically put him in his seat.

He should he listen (with no ice cream) out of respect for you as the parent?  You would probably go grab him and escort him to his seat, and physically put him in it.  Now, children are different than dogs because we can verbally negotiate with children... We cannot say to a dog "if you don't listen, we're not going to the park tomorrow!" They don't understand those concepts of negotiation. Everything has to be immediate and consistent, and praise and rewards should only be given if they are deserved and earned by appropriate behavior.

Dogs communicate by body language and they are physical animals.  The physical touching of teaching obedience will help him get over his fear and accept human handling.  When it comes to his owners, it is not a dog's right to decide if he wants to be touched or not.  Like I said, you want to work on this now because it will not get easier as he gets older.  You might end up with a 85 pound Shepherd that you cannot even touch or control.

I also realize you have only had him for 2 weeks, so he is still getting adjusted.  He will need to bond with you, and spend more time with you.  One easy way of bonding is to hand feed him his meals.  Sit down, hold the bowl in your lap, and hand feed him his meals.  Play is also a way of bonding, try to find a toy he loves.  Doing obedience together is one of the best bonding experiences.  Then once he trusts you completely, you can work on his fears of strangers.

Sorry this was so long, I kind of went on a tangent with the training theories.  Good luck, and good for you for adopting a pup!