Black Lab growling at people, Including family

Question
I have a 4 almost 5 year old male black lab, he is not neutered. He has recently started growling at people who have come to our house millions of times he will go to them and act like he wants petted they will be petting him and he will start growling and the hair will stand up from his shoulders to his tail, he has also done this with me. He gets tons of affection and daily exercise. We got him when he was 8 weeks old. Can you please help we don't want to get rid of him but feel for the safety of our children who are 5,7,and 9 that we may have to.

Answer
I am glad you didn't give up on me.  

Usually a dog's personality is fairly stable after they mature at 3 years old.  Something has happened.  Can you think of any changes in the home or bad incidents?  He could have a physical problem, his hearing or vision could have gone bad.  People could be touching a tender spot.  Take him into the vet and discuss the problem.  Go ahead and neuter him.  Aggressive dogs should never be allowed to breed.  

If none of the above helps, try obedience training.  With somebody the right age in the family, 4-H dog training is a great idea. In my area, clubs form soon after the first of the year.  Even many urban areas have 4-H.  For info look in your phone book under government listings for extension or cooperative extension offices.  Ask specifically about a dog or canine club.  The dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class.  A good obedience class or book is about you being top dog, not about rewarding standard commands a treat. Start at http://www.dogsbestfriend.com/
For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm