6 year old Poodle growling and snapping

Question
I just acquired a 6 year old male Poodle -- not fixed.  From head to floor, he stands about 12 - 15 inches.  Not sure what classification he is (toy, etc.)  I have two sons, 10 and 12.  He had belonged to my mother-in-law.  She had him for three years.  Unsure of the history before that.  He is very sweet, wants to have a ball thrown for him constantly and seems very happy.  He eats and drinks well and does his business normally.  No accidents in the house.  He immediately attached himself to my 12 year old son.  On several different occasions, he has growled and snapped at me if I come near him when he is with my son (i.e., sleeping under his bed, laying under the chair that my son is sitting on while on the computer).  A particular incident happened this morning.  My son was laying on the couch and I was sitting at the end by his feet.  Our Poodle was laying against my son near his stomach/chest.  I got up to get ready for work and gave our Poodle one last pet before I left.  He growled at me, and when my son said, "No!," he turned, growled and snapped at my son.  Would getting him fixed at his age help this aggressive behavior?  Is it too late for training?  I've been reading a lot about hierarchy -- alpha dog, etc.

We love this dog and most times, he is very sweet and gentle.  He lets my younger son carry him around -- my son doesn't do this often.  Both of my sons play with him a lot -- throwing toys he likes to retrieve.

Appreciate any help!  I am a single mom.  Just bought a house and am waiting for the first-time homebuyer incentive.  Once I receive that, I'm taking him to a vet for a health check and to get him fixed if you think that will help.

Answer
Hello Denise,
While getting your dog neutered is good for the dog if you don't plan to breed him, I don't think it will help your situation much.  It might lessen the aggression, but may not either.  Still, if you are taking him to the Vet anyway, it would be a good idea to get him neutered because it makes your dog more healthy.  
What both of you need to do is to dominate this dog.  When he growls or snaps at you, you need to hold the dog down in a submissive position (laying on the ground with his head on the floor) until he relaxes, look him in the eyes until he looks away, and when the dog decides to submit then you should just walk away and let the dog up.  This shows the dog that both of you are the Boss and that the dog needs to respect you.  Even if your dog tries to bite or get more aggressive you need to continue to do this.  He can't be led to believe that he can get away with any aggressive behavior.  If he thinks that he can scare you by snapping, growling or biting, he will continue to get worse until he controls you.  

You might also think about getting him into an Obedience class.  It will show him that you are in control of him, but at the same time, it is something fun for the kids and the dog.  Poodles do great at Obedience, it gives them an out for all their energy, and most Poodles really enjoy it, plus it will make him a more behaved member of your family.  

Try these suggestions and if you have other questions or concerns for me, please feel free to ask.
BTW, according to the size you say he is, I would consider him a Miniature Poodle.  Miniature Poodles are anything over 10" at the shoulder and not over 16" at the shoulder.  

Thanks for using AllExperts.com,
Kim