Great. Thanks for the additional information. I really appreciate it.
Kittens learn how to interact with their environment through watching their mother and siblings and by play fighting with them. If this kitten is truly only 1 month old, then it's possible the hissing you're seeing is because she doesn't know how to correctly interact with you and her environment.
If she truly is only 1 months of age, then I would have to urge you to get her back with her mother and littermates so they can teach her how to interact correctly.
If she's actually older than 1 month of age, then it's possible the hissing is actually her playing and you're handling things exactly right. When she hisses at you, the best thing to do is end play time so that she learns that bad behavior means the fun ends.
Kittens aren't like puppies who crave our attention. Cats are, by nature, really independant, so odds are she's decided that your son is her favorite, and may really never warm up to anyone else. But that can change too.
At this point, I wouldn't worry too much about it.