It's human nature. Humans have a unique (maybe its not unique?) sense of self. This sense of self gives us empathy for others and other things ("what if that we're me..."). I think all of our morality is driven by this. Take away empathy and i think humans would behave very badly.

I believe in evolutionary morality, or the theory that morality is evolved for the purpose of advancement of the species.

To make my point short and sweet, I believe selfishness, self-priority, maliciousness, malevolence, were all things that were and are used by primitive or misguided people, thinking that they need or needed to behave such ways to advance the species, as the survival of the self does help the species perpetuate.

But, evil such as that is now, well... evil, and for a reason.

Group-priority, selflessness, benevolence, compassion... I earnestly think these are all vastly more effective for an advanced civilization to grow and prosper as it evolves. Thus, good and evil are both factors of our existence, and I think we will overall become more 'good' as time goes on... or we will destroy ourselves.

Humans are social animals, and as social animals we tend to be do what's "right" or "wrong" based upon the DNA encoded into the individual and the environmental circumstances.

It's known that ants, bugs, birds, dolphins (to name a few) make "choices", both "good and bad" for themselves; they know what they need to do, very instinct based and less "free-will" based, like us.

Either way, we're all making choices based upon situations and circumstances and the DNA code of our being.

Absolutely, human beings are naturally moral creatures, but what people said about 'right' and 'wrong' is different to this.

If one man thinks killing his daughter because she had sex aged 16 is morally sound, and one man disagrees with him, who is morally 'right'? Nobody. There are no universal morals to which we all are bound - each individual has his own (unless he takes direction in this area of his life, from religion or other sources). It just so happens that most of the time, the majority agree on a particular moral issue and so we form laws, forbidding things such as murder, rape, and theft.

But even if 99.99% agree on a particular moral issue and there is one outlier whose opinion juxtaposes that majority, he is no less 'right' than the rest.