Et in Arcadia Ego
We are all 'born' neutral. What we learn as we grow up, is what we determine makes us 'good' or 'bad,' and how we apply it. The problem is, usually, since we have seen this 'choice' all our lives, we don't recognize it as 'good' or 'bad,' but how we are supposed to act toward each other.
The Ego is basically who you are. The "I" in your 'life.' How it acts in your life is the positive or negative side. Thus, if you suppress your 'I,' and help someone else out, you are 'good.' If not, and you only think of yourself, we tend to see that as 'bad.' A 'true,' and almost impossible, neutral person would have a perfect balance of self sacrifice and self indulgence.
An example of the perfect positive Ego would be Christ. A life devoted to helping others, even to not trying to save himself at the end of his mortal life. The opposite would be the Anti-Christ, who does nothing for anyone without a self-motivated reason for every action and has, er, uh, yet to come. Geez, keep forgetting the dates. :)
The most common problem with the Ego is that it leads us to to do things that we might not be able to do. Often, the military pushes us to see how far we can go (as can life), but this can instill a false feeling of confidence. This can lead us to take on tasks we can't do. The best example I can think of is the typical male Ego, taken to extremes by the police and others who don't know their limits. Usually, these types start out in sports, which massages their egos with glory and women, then into the military, and finally into law enforcement or something else that is highly glorified by some groups. Eventually, they will try something insanely stupid, such as a single arrest of a gang or dangerous criminal, and will cause serious harm to themselves or they lesser brethren.
The opposite is also true. Those who were attacked in school, picked on, and generally made to feel inferior can have such a low self-esteem, self-worth, and low Ego, that they feel they will never be able to do anything, and are often severely depressed. Thus, we can see how we 'learn' our value by the world around us, and not how we are born.
Gee, did I answer your question? :)