Nature vs. Nurture

I've been pondering, lately, the nature of people.  Is our bad behavior nurtured by nature?  Or is it simply our nature to nurture bad behavior?  There are very few of us who still open the door for others - especially for Moms pushing a stroller.  I mean what kind of person stands and watches a Mom struggle to open a door while trying to push the stroller at the same time?  Oh that's right, the kind of person that goes through the door you just opened for yourself and the baby you're pushing before you can even go through.  I digress.  I believe that there are so many persons out there that continue to behave badly towards others because people like me allow them to do it.  And why do I allow it?  1, I'm not the type of person that likes to rock the boat.  2, I care too much about what other people think/feel about me and so I shut my mouth hoping that they'll realize/learn that their behavior is not something that is warranted.

I would have to say that I'm a very good natured person- I'm usually the volunteer for anything that needs to be done.  I am willing to bend over backwards for a person I care about... that is until you screw me over.  I don't believe in forgiving and forgetting.  Why?  Because in the past, I've usually been the person forgiving and the other person is usually the one doing the forgetting... and so very often we end up at the same crossroads again.  So I have turned a new leaf.  I've stopped living with the thought that if I do good to this person I expect/hope that they will do the same for me.  Now my philosophy is -- everyone out for themselves.  The problem?  I can't turn my expectations off.  That has been my problem my whole life.  And that is why I have been disappointed my whole entire life -- with the exception of a handful of people, Hubby, Baby, Mama, Papa, Brother.  

And so where does this leave me?  Do I let nature take its course?  Let 'karma' or some higher source teach these persons the lesson they badly need to learn.  Or do I nurture my own bad behavior and do unto others as they have done to me?  That is the golden rule isn't it?