3 year old yellow labrador

Question
We have a 3 yr old yellow labrador male, neutered and very soppy.  I think I might have over spoilt him and treated him like a baby,(perhaps this is the reason, as he might be trying to protect me) he has been to training classes and is obedient,  but he seems very scared of new people, he lurches forward, growling and looks like he is going to bite them, even children ( he has grown up with my 11 yr old son so is used to children) It is a worry as i am scared he will actually bite someone.  He is ok with people he knows.  He is quite a scared dog,but he has never receieved any ill treatment and is so loving and lets my son do anything to him.  I wonder if you could give me any ideas as to what I can do to stop his behaviour, and to what could have caused it. Thank you.

Answer
Likely the problem is early socialization, meeting too few people before 12 weeks old.  Neglect in the important 6-12 week period may never be completely undone.  Starting at 3 years will be even more difficult.  While he is obedient, he doesn't see you as the leader protecting him.  He feels responsible to protect you.  It is unfortunate too many obedience classes concentrate on teaching the dog commands, and fail to teach the owner how to play the role of the leader.  A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm  That site has some additional material on dogs and children.  

One thing that will help is to arrange to meet strangers to him that have treats.  As for others, keep calm.  If you let it stress you, he will senesce it and blame it on the stranger, confirming they are a problem.