Lets start with the following accepted as a given:

• There exists no supernatural forces in the world and there is no objective morality imposed from above.
• Our current moral codes are currently based on some mix of sociobiological influences & cultural forces

Of the current figures who accept these premises, most espouse some form of secular humanism which argues that humans are genetically programed not to lie, murder or steal, therefore this is both the right morality & the one they practice. This, to my mind, is committing the naturalistic fallacy.