Traditionally, morality and the question of right and wrong have been the province of religion. More and more people do not identify as religious or follow a particular religious teaching. Useful for consideration: Aristotle's Virtue Ethics, Moral Relativism, Abraham Lincoln's essay on the importance of upholding the law, Martin Luther King's Letters from a Birmingham Jail, Utilitarianism, Deontology, Kant's universal law.
In philosophy, there is a concept called moral relativism. It was particularly popular in the mid-twentieth century, but has fallen out of favor in many circles today. Aristotle's famous question - "is conduct right because the gods demand it, or do the gods demand it because it is right" - is answered in moral relativism with a resounding no, to both alternatives. Instead, moral relativism asserts that conduct is right so long as it is in keeping with the conventions of the culture within that conduct takes place, and conduct should only be judged within that context.