I bought a GSD that is 1/2 German and 1/2 American bloodline. It seemed very confident at the kennel but when I got it home it became very shy. Is just an environmental issue?

Ed, I've been doing research about work line GS dogs. I am really impressed with the work that you've done and your time dedicated to GSD's/training. Hopefully you can answer a question of concern to me about my new german shepherd. I have recently acquired a 1 and a half year old shepherd from a mix of German and American working lines. The dog was to be used as a stud since it exemplified excellent physical lines and temperament as an alpha of it's litter. I ended up getting it neutered. The few times that I visited the kennel with a friend, the dog was very social with me (a stranger). The dog grew up with many other dogs, but was properly separated to prevent pack aggression. When I took the dog home he bonded with me, but seems to be very scared of everyone else... even the members of my family. He seems to run away when someone else tries to pet him as if he was scared or timid. This definitely does not seem to be the same outgoing, sociable dog that I first met. Do you think it's an environmental thing and that he'll grow out of it with increased socialization? Or do you believe, this will be his personality for good? Like I said, it did not seem at all timid when I first met him. I was told that a timid shepherd is not a good trait...thx ...ALF