Jiminny Cricket

Yesterday I was talking to my wonderful, amazing, awesome, talented sister about (well, sort of) guilt. I told her to look deep inside herself and try to see where those thoughts are. Then I asked if she really feels those things or is it just because she thinks she's supposed to.
This was a good realization for me to have. I think maybe I feel it because I think I'm supposed to. Isn't it what we're taught in Sunday school (or somewhere)?
I have a beautiful painting of a woman from the back. She is under some sort of blanket but is not dressed. I don't even think of it as nude, but I guess that's what you'd call it. When I bought this painting, I lived alone in my sunny studio apartment with vaulted ceilings. I was finally, at 25+ years old, discovering my self esteem, my femininity, my own thoughts and feelings. To me, this painting is of femininity, strength, beauty. I LOVE this painting.
However, when I got it, I was so embarrassed that anyone (mostly my dad, nephew, or home teacher) would see it. I was sure I'd have to explain all my innermost thoughts and feelings and what it represented for me to everyone else, which basically kills any of those thoughts and feelings. I acted embarrassed but, in this context, I don't think I really felt it. It's like I acted it out because I was "supposed to." I couldn't buy the painting and have it in my home unabashedly. Nudity, nakedness, even art and passion and emotion, are bad so you have to feel guilty.
It's a big thing for me to realize that I didn't really FEEL the embarrassment/guilt. And to realize that a lot of my behavior, talk, actions are based on that expectation.
In a way, guilt is a blessing. It lets you know when something is wrong. But if I can feel it even when I don't really think I'm doing anything wrong, how can I trust it? (As I type I think that more of a guide for me is understanding what's wrong with it or, more importantly, it feels not right, there's discomfort, and that is not the same as guilt).
This is all interesting and good for my thinking but I'm quite interested in where this all comes from. Not why we feel it, but why we act on it and accept it as such truth when really, it could be wrong? We live beliefs, we act out feelings, only to find out they're based on... what? nothing important anyway. And it leaves me feeling like where is my conscience? Do I even really know what it sounds like? I think I do because when it comes down to it, I've done right things for right reasons and for my own convictions, but other times? What is this drive? this... shame? that so controls me?