Do you really believe people can be genuinely altruistic?

In this question some people said they do not believe people to be able to act truly unselfishly. I currently share and have always shared this view, considering that introspection makes clear that about everything I do that would be “the Right Thing” is, in the end, to make me feel better about myself.

To be honest, I don’t really think this is a bad thing, as Good Things still happen this way. It also allows me to believe in “the goodness of man” because I believe most people feel better by helping others. Even if that means it is ultimately selfish.

However, what do you think? Can people be genuinely altruistic?