Personally I'd like to take religion totally out of the equation. As a lapsed catholic I know a few things about all this "original sin" baloney. The way I look at it is people are born as people. Some of us have genetic dispositions that lead to alcoholism, schizophrenia, intelligence. good looks etc etc. We're born primarily with selfish and ego centric (self preservation) instincts as well as capabilities for love, kindness and all the other positive aspects of human nature. Either way we also have the luxury of choice, we can make conscious decisons to do good or to do bad.
The nature nurture argument is very relevant here. No doubt we have inherited genes that already point us into developing along certain predetermined lines but our environmental and family circumstances play a very large part in determining what we are and what we are to become.
At this stage in my life I am committed to removing as much religious dogma from my way of thinking as possible. This doesn't mean to say that I refute all things religious and therefore God. All I have to do is a bit of star gazing to realise that the possibility of a creative force behind the universe isn't an impossibility but I also do believe that the jury is out regarding God and indeed if God exists, the nature of God.
I believe science can answer most of our questions regarding the physical world even if it is currently unable to answer the most fundamental questions. Most of us now believe in evolution (though there are many exceptions), most of us now believe that the earth revolves around the sun.
To summise I believe that human nature is definitely a mixed bag and not a black or white option.