You feel guilty because you've been told that it's a sin.
No, deep down inside us all, we all know when it comes to doing something wrong everyone feels guilty for when something bad happens. Also deep down inside everyone's heart it groans for a relationship with the Creator.
Because you keep trying. That's why anyone would think that you have an answer for everything.
Just because I try to answer people's questions doesn't mean that I always have an answer for everything.
I don't ask you questions to get your knowledge. I ask you questions in the hope that you will question your knowledge.
I do question my knowledge and what I believe and I find it answered by what God has shown my through scripture and evidence from apologetic people.
God made Adam and Eve and God made them in their own image. God made knowledge of good and evil a sin. Now everyone know's what's good and evil and that's why sometimes when you or I know we did something wrong we feel guilty for what we have done.
I am not ultimately sure why there was a tree of knowledge of good and evil but I assume that God wanted to test them. But then again, I am not God but there is an explanation of why He put it there. Why does everyone think I can answer every single question when it comes to explaing about why God did this or that? I am not God!!