If God made us I'm pretty sure that we haft to know at least something on how we got to this planet. We are all God's Children and it's the first thing any Christian will learn and die knowing, and if you really don't buy it all you can do is read THE BIBLE!
You may have heard of the Scientist/sociologist who has been doing puppet shows for infants in the news lately. Her theory was that an infant human child was born with the knowledge of good and evil, versus learning these habits. Her test, in the most simple terms, was to show them a puppet show of puppet bullies being mean to other puppets and then allow them to choose which puppet to play with. Her results were clearly indicative of inborn knowledge of good and evil. Almost every time, the infants chose the puppet who had been victimized to play with, and flat out avoided the bullying puppet. You may chalk this up to a desire not to be victimized themselves, but child abuse cases prove that even when victimized themselves, a child will still seek love and affection from the perpetrator. In some cases, the infants involved in this test not only chose the victim to play with, but they actively showed warning aggression towards the bully puppet, as if admonishing him for his behavior while they protectively cuddled with the victim puppet.
If this isn't clear and present evidence that at least SOME morality is inborn in us, I don't know what is.
Further, if morality was a learned habit, how could one explain a child brought up in a distinctly immoral environment to be a very moral individual? Frequently in child abuse cases we see that the child becomes the antithesis of the abuser, actively seeing out moral attitudes and behaviors in spite of their most influential role model.
To quote another of my opinion arguments: 'What Heaven has conferred is called The Nature; an accordance with this nature is called The Path of duty' (Doctrine of the Mean). Mother Nature has given humans the gift of the Nature. Humans are by nature benevolent; Mother Nature has endowed upon us the abilities of benevolence, righteousness, propriety and wisdom; to adhere to these principles at all times is to follow the Path, and to follow the Path is what morality is all about.
It is not through nature that we learn how to live, rather, its through nurture. If our behavior and up-brings are through nurture, then no human is born with a set moral nature, rather we create or build the path of life we want to live through nurturing the life we find suitable for us
The only thing that is "nature" about it is the ability to have opinions about the way things ought to be. Throughout history we've seen practically every variation on this. Slavery is moral, then it's immoral. Human sacrifice is moral, then it's immoral to even execute someone for murder. And there's been silly things like "no work or play on Sundays".
You live in a starving country with no resources and few currency reserves that is desperately in need of education. What do you do?
Historically you get involved in a long genocidal action. I think if morality were inherent you would work together to fix your problems, but no, in prison, during famine, disasters, whenever there is a breakdown in order THEN people reveal their worst nature. They sell out their neighbor, overcharge for needed goods, hurt everyone around submit to degradation for survival. Obviously morality is not something we are born with because the loss of running water and power makes most people psychopaths.
Social laws, that is. It tells us what is right (acceptable) and what is wrong (unacceptable). The only difference between it and our written laws is a) they are unwritten and b) they focus on psychological punishment rather than anything physical. It's a system created to keep unruly individuals in a social group in check, another way of enforcing the "norm".
It's actually quite a complicated topic and I don't feel prepared to get in-depth on it right now but that's the gist of my view on it. Basically it echoes GoodPoint's above.
I believe we begin with a set of core instincts: to provide for physical and mental health, to maintain social interaction, and the urge to resolve cognitive dissonance (Confusion of action and desire). Surrounding these instincts come morals, usually derived from nurture. Some people are raised in environments in which they must adapt to defending these instincts. When the need arises to kill, they are aware that in order to thrive they must do so, and so they resolve their cognitive dissonance and proceed. Others are raised in environments where these instincts are either defended for them, or tied to those around them by teaching or relationship building, these individuals have the opportunity to branch away from their core instincts and allow them to make "good" choices. I believe the black and white we refer to as just and unjust are simply different ways of rationalizing our actions, and that the only reason good is good is because it has so far proven to be the most effective way to promote social interaction. Eventually though, weather it's effective or not, the events in humans lives can lead to any moral ending. There is a major section of psychology dedicated to analyzing a persons past and seeing the shadows it casts on their present mind and choices. Seeing that proves to me the nurture is to blame for our moral teachings, and I thoroughly believe that if not taught morality, a human could end up going either way on our imaginative spectrum, without being aware that it is right or wrong.
I think that as mankind grew, we created morals. We created these morals in order to survive, in that without morals we wouldn't have laws. Due to the fact that laws are based on logic and morals. Take for instance that it's illegal to kill. Would we have created this if we did not have morals, and did not see it as right or wrong? I think we always have had a conscience which tells us the morality of our actions. However, we had to develop our conscience in order to understand it and use it to its full extent. This is why I think we had a basic understanding of morals but ultimately had to create it, develop it, and adapt it to fit what we now know as morals.