In my opinion ethics are those principles that each person define inside of his or her mind.
The objective with those principles is to create a kind of guide for life that let you know if you are doing something good or not.
I think that the principles are made of values and we build them depending of the next characteristics:

• FAMILY: Principles depend of the family, because some families give more importance to some acts than other for that reason the values changes and finally the principles change.
• CONTEXT: Because the society start defining what is better for the most people and that give us a perspective about what is good or not.
• OWN PERSPECTIVE: In this step, our ethic is not in function of our family and the society, is in function of ourselves because we also have the possibility to build and  determinate what is good or not depending of our judgment.