Fearful Kitten?

[SammyCat]

I recently adopted a female kitten. Her name is Sammy/Sam for short. I think she's a medium grey/black/brown haired tabby. Since the moment Sam entered our house, she never comes out. She hides down stairs. I don't know whats wrong with her or if hiding is in her nature. Anyone here know anything about this or can help?

Here is the kind of kitten I am talking about. She is 3 months old btw