This is an excellent point. However, without a 'ten commandment' framework, how does a parent guide their child to "what is right". By whose standards? Because "I say so."? It works when children are small but once they reach the teen years, they heed their own small voices and predicate their decisions on what the government schools have taught them. I am most curious to see how this plays out with some of my coworkers who are in precisely that situation.
That is a fundamentally religious question. Rather than ask 'By whose standards?' try asking 'By what standards?' and whole schools of philosophy open up to answer the question. There are lots of answers to that question, but let me just say that there are two fundamental rival schools (within philsophy) that have been duelling for millenia. Virtually all philosophy developed from either Aristotle's ideas or Platos ideas. In addition to their religious beliefs, our founding fathers were well versed in Aristotilean rooted philosophy. Virtually all of modern academic philosophy (and European) is Platonic.