Does every family have that one kid?

I have 4 kids. There is this little girl I have, that is now 13.  She always has her nose in a book. She is always in her room. She loves to be with friends and having fun, but when she is home, she is always in her room. I ask her what she is doing in there all the time. Heaven knows she is NOT cleaning it! haha
I worry about this. My other 3 kids tend to gravitate to wherever I am. Not clinging to me, but in the same room or vicinity! I don't know what to do with this kid. I worry about where this is going. I am worried she is spending too much time alone. Not to mention, I wish she was involved with all of us more. Not sure what to do.
If she is like this at 13, how secluded will she be at 15? 18?