Why would a Capricorn be hesitant about revealing entirely his or her true self?!

Why would a Capricorn be hesitant about revealing entirely his or her true self?

I love all these answers - I think they do all apply. I don't really think of myself as secretive, but several times in my life, people who I've worked with for years have looked at me after I've said something and said something like "wow - I didn't think you were interested in that". It's been with music I like, people I know, or how adventurous I am. To people I know well, they're just as surprised by these reactions as I am.

I think it is trying to keep my professional life professional (they don't need to know what I did last weekend, why should I talk about it?) and don't think strangers should know about my personal business. There are too many people out there that will tell you wayyyy too much information. I know I am slightly repelled by that and try to go the opposite direction.