Growling and biting in 6 month old

I have a 6 month old kitten. I got her when she was 2 months old. She was the only kitten as her littermates were killed at around birth by a dog.
I have a big problem with her, she is a sweet and playful kitten around our family(me my husband and our 4 children 14, 11,7, and 2) But as soon as a stranger comes over the kitten will growl and hiss and try to hit, scratch the person, adults and children. The cat will not hide but follow the person around and act aggressively.
At Christmas I had about 12 people plus my own 6 over, so quite a large group and the kitten was growling and hissing at everyone, it would sit in the middle of the group while we were opening gifts and growl, but not run and hide.Until I finally put her downstairs. I was holding her and she was purring and happy and my mother in Law, (who has had animals all her life, from Siberian tiger to deer)Went to pet her and the kitten tried to bite her.
And then yesterday the kitten had jumped into a drawer of my sons that is by his Chincilla, and I went to take the kitten out and it put her ears back and hissed,and tried to bite me, this was the first time it was aggressiev towards me.
The cat has been vet checked. I dont know what to make of this behavior. We do not have any other cats or dogs, and she is an indoor cat.
Any suggestions, I dont want anyone geting hurt by my cat, and I just can't figure it out.
Thanks in advance
Lynn

Hmm sounds bizarre.. is the vet sure that there is nothing wrong with her? Alternatively, it may be that when she feels crowded it it has something to do with her early months. It could be that she is extremely possesive of her new 'family' - you have replaced her feline family, and it could be something to do with that.

Is she spayed?

No we have not had her spayed yet, I was told to wait until at least 10 months.

My cats were fixed at 4 months. Is there a reason why you were told to wait until 10 months? I think spaying her will reduce some of her behavioral problems.

Originally Posted by momoffour

No we have not had her spayed yet, I was told to wait until at least 10 months.

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Spaying will help. You do not need to wait until she is 10 months of age...the rescue I volunteer with spays at 10 weeks of age so that the kitten won't ever experience "heat". If you tell us what state you live in..I can look up some low cost clinics for you.

Katie