Many people confuse ethics with morals, laws or social values. They are neither. Although influenced by these things, they are separate. They are agreed upon guiding principle(s) of a professional body, such as those possessed by doctors, psychologists and so on.
Ethics impact Human Growth and Development through the influences of the professionals who work within its context. Simply said, the ethical professionals who work in the field are the ones who drive and influence the knowledge and principles of the field of human growth.
One such example would be the way that information is gathered in the field. Let's say that a researcher has a very good theory on why autism exists. He feels that toxins in the environment are the cause of the disorder. In the case where ethics did not exist, the researcher, feeling the end benefit justifies the means, arranges for three women to unknowingly be given injections of a heavy metal toxin. The women have children who develop autism, the researcher publishes the results and becomes famous. However, ethics within the profession indicate that justice, veracity, and beneficence outweigh any methods that would cause such harm. Therefore the researcher is condemned, not applauded.
Ethics do not limit our knowledge, they make the process of gaining that knowledge fair, equitable and just. The entire field uses ethics to decide if privacy, confidentiality and informed consent are being applied as they should. Basically, ethics support fairness, safety and yes, even the overall knowledge of the field. True, we could learn much in a very short time by avoiding ethical codes of conduct, but the damage to the individual would be too great.
In the end, ethics supports the individual client; the need for stability and truth with in the field and the safety of those involved in research. And, most importantly, the ethical codes within this field must show aspirational views, not just minimum standards. Ethics guide, protect and serve....the clients. As a result, they are the professions most sacred tenant.