I think it's the opposite. Society tries teaches us that self-sacrifice and being selfless is a good thing and we feel good about doing it as a result. I think if it were innate in us, we would all be doing it all the time, but we don't.
I do find it odd that a group of people who more or less think the world has gone to sheet and is only getting worse, which I think is an apt description of most of the regular posters on the EE, believe that people are basically good. I wish i felt that way, but I just don't see it in people. In many ways I think we are where we are because the people in charge have used those base human instincts to gain favor and political support.