The concept of moral relativism has attracted attention to those looking to justify behaviors considered immoral by others.  The argument states that morality is relative to each individual and no absolute authority exists.  The primary argument against moral relativism is that a sacred doctrine, depending upon the religion, provides absolute authority on moral matters.

The truth is that morality has always been based on health concerns.  Abraham got circumcised when he was 100 years old, and apparently that enabled him to have a son.  So circumcision became a foundation moral practice in Judaism.   Various foods would cause illness if eaten at certain times of the year, and so the basis of various morals concerning diet were established.

It goes without saying that killing people is generally unhealthy.  The health concerns of the elderly inspired the morals of honoring one's parents.  Sexual promiscuity eventually results in hard-to-cure genital diseases.  Sex practices other than simple and gentle coitus will often cause physical injuries.  Thus moral rules governing sex practices within a community were established.

Well-being is happiness based on health.  Health is the absolute and underlying authority governing morality.  A moral person steadfastly lives a healthy life.  

Religions naturally incorporate healthy actions and behaviors into their dogma, as morality provides the happiness and freedom from suffering attributed to the Giver of Life.  But so also do governments, fraternities, schools, long running and successful businesses, and other groups of people.  Naturally, every family wants health and happiness, and so concerned parents teach morality to their children.

Whether people understand what morality is or not (and most do not), they instinctively know they must act in ways that promote health and well-being.  It is the nature of the living to want to continue to live.  Through trial and error, all living things learn the behaviors that lead to good health and well-being.

As long as life continues, morality will always be the central cultural theme.  Even if a fad arises pretending that morality will conform to political preferences, in the end, morality will again be defined as the health and well-being of individuals and communities.  We can fool ourselves, but we cannot fool nature (or God.)