How did I develop such a strong need for attention?

I never fully realized it until now but I desire love and attention all the time! I'm the type of person that is overtly touchy...I hug everyone all the time, and cling to them. I will act goofy or flirty just so I can get attention. The main reason at first for me becoming a model student was for attention. I get homesick really easily when away for like a week or more, to the point where I have anxiety! I don't like being alone, it upsets me...I need a lot of humans present around me. I don't know what caused this in me. Could it be a childhood experience or just an inborn part of my personality. I don't like it!