My pup will be a year old next month. He's very loving and great with kids, although lately he's becoming a little aggressive with new comers in the house. those who he has met he lets walk right in, but now when we bring others in he doesn't know he tends to be mean. he's jumped on two of my friends in a non-friendly way, attempting to bite but never locking down on them. I'm not sure why all of the sudden he's acting like this but I have many children around and don't want him to get aggressive.
Sounds like he needs to be socialized some more. If he is UTD on vaccinations you should take him out. He needs to meet strangers and be rewarded for behaving. PArks that allow dogs or just a walk through the neighborhood on a leash. Take treats, when you meet someone that would like to say hello ask them to go slow. Give the new comer a treat to give to your puppy and praise him for taking it gently and being polite. If he shows aggression, he is told "no" and walk away. This takes a lot of practice and time but you will be rewarded in the end with an awesome, well behaved dog. Good luck