Ah, you are right. I tried to convert my father a very long time ago. I do no such thing to anyone anymore. I don't know how to identify those who "have no religion." I just remember a while back some kids on my bus were debating religions and when someone asked this one boy what he beleived he said "I don't know. I haven't thought about it much." I guess the only way those who try to convert people would know would be by talking to people.
I do agree that most human beings would not be as enlightened.
Sorry, I don't have a more definitive answer about the parents. Maybe one day when I have my own children and if you're still around here, I will have a better answer.