Is it weird to talk to yourself? Or have conversations with yourself?

[G?g?'s L???l? M???†?r?]

Hey, I'm 16, and since I was a little girl...I've had a really bad habit of talking, and holding conversations with myself as if someone was with me, listening. I always knew no one would ever respond back, but, somehow I still talked to myself? Now that I'm in high school and I STILL do it, I can't help but feel that it's odd...o__O I mean, I have really good social skills (I have a lot of friends--its not like I'm a loner, haha) and I don't think I'm necessarily crazy (maybe I am, who knows). I heard from somewhere that it was a sign of intelligance? I've been in the gifted program at my school since 1st grade, so I guess I'm somewhat smart. I guess I always spoke to myself because I never had any siblings or anything like that growing up, so I would kind of just...speak to myself instead. I feel like a freak, though. Is this normal?
Also, could lonely ness be a key factor in this? My mom is always working, and I don't know my dad, so I'm always home alone...