Luis,
It may be disappointing, but I really think it's for the best if owners deal w/the reality about their dogs' problems. As a general rule, if the dog shows aggression in response to a neutral, non threatening human, the dog is a spook dog. The fact that he doesn't back down is likely b/c you are right there, giving him just enough confidence to act out. If someone broke in to your home and you weren't there, these are exactly the dogs who would run and hide under the furniture. Work on building his confidence and accept that the pup may be the better prospect for true protection.
I really would limit their time together, tho. I would hate to see a good pup pick up on the adult's behavior and think it's normal. I've got a bitch pup like that (Mink g-daught.) If the big guy, Thunder is at the fence barking at someone, she jumps right in. If he's not there, she just wags her tail, watches for a few minutes and goes back in the house.

Ahhh, Vince. Good point about finding a diverse group of humans! And don't forget wheelchairs, esp the motorized ones, walkers, canes, etc.

Good morning Thunder,

You are making more sense as I read you posts. I have long excepted the fact that Max is a fear biter (or at least I suspected it)... one good thing about Max is I trueing believe that if you got in the house or came at the wife/children you would have one hell of a problem... he's a 90+ lb. male. The pup is tremenduosly diferent in temperment. He shows alot of confidence in himself. I'll work him as a pup for drive but I'll leave the protection training to the pros. I'll finish reading your site today, if something doesn't sound right or if I have question I'll hollower at you. If I can figure out how to post pictures of the two GSD's I'll do it.

PS; I'm also planning on taking Max out to the general public... maybe I can break him of viewing everyone else as an aggressor.

Best regards,

Luis

Luis,
In addition to all the excellent comments by everyone else in this thread about the importance of early socialization, I wanted to add one more thought. The early socialization of pups affects the working ability of dogs when they are grown up. This was proven by the pioneering work done at Guide Dogs for the Blind, Inc. They found that dogs who were undersocialized as young pups had a high failure rate as guide dogs; these dogs would often fail the crucial test requiring them take responsibility for their blind owners. These were dogs from the same breedings as those that passed, so we know it wasn't genetics. These dogs had all received the same training. This is documented in Clarence Pfaffenberger's excellent book "The New Knowledge of Dog Behavior". Whatever goes on in the pups' heads from this early socialization is probably equally important for any working dog or companion dog.

Since your pup is 4 months old, you have already missed out on most of the early socialization period. But it's not too late, and the sooner you work on this, the better it will be for your pup. It becomes much harder to socialize a dog once it reaches adolescence, and that's when the damaging affects of undersocialization of pups often starts to rear its ugly head.