The Human Conscience

Kind of going along with parts of class discussions and other blogs I've seen I've been wondering about the human conscience. One question that could be posed is "do we all have consciences?" there are those who do not due to mental disorders, not knowing right from wrong but if the majority do have a conscience then...where do we get them from? Do we develop them from how we are raised and our surrounding influences (parents, educators, religion)? Or do we start out with the basics for a conscience and it is then formed from our worldy experiences?

My question, in short, is...do we greatly rely on our conscience and, if we did not have them then would that make us evil?