Yes, I certainly believe that our morals come from an outside source. That's a given for a Christian, obviously - the bible says we were created knowing right from wrong. But I know I can't discus the issue from that perspective here, so I have been trying to discuss it more from an individual perspective - by that I mean, trying to isolate what we do, think and feel as individuals, and trying to grasp why that is.
I certainly understand what you are saying, and you make a strong case. I just feel though that it doesn't really explain a lot of our behaviour. In fact I think it goes much deeper than observable social behaviour but rather is rooted in our feelings. ( I'd like to say morals are 'written in our hearts', but I'm trying to keep my darwins to a minimum ).
Re/ sensing that others who don't see things my way being part of the problem, i don't think that is the case. I do believe that I'm no different to most people in terms of my reactions to authority, reactions to injustice and evil, desire to be a better person - i base that belief on my interactions with people over 30 years.
And I just think that there are so many behaviours that we recognise instictively as being wrong, and would do regardless of what we had been taught.
This whole subject is a difficult thing for me to try and communicate my perspective on, and I'm starting to run out of puff, truth be told. Theres a lot of other stuff on this site thats piqued my interest.