When I was a kid, all I did was give. I gave until I had nothing left to give. When my mother found out about it, she would always yell at me and ask, "what about you? How are you going to survive without X?"
Truth is, I never thought about the consequences. I just knew that if I gave someone something they needed, that was all that mattered. And it felt good.
I'm 29 now and my mother is late. Things are different. I am the most selfish person I know. I always give less than I want to give. Sometimes, I just outright say NO. But that's because I am trying to build a life for myself. I am saving for marriage, a house and my business; so I hardly have anything to give anyway. I always tell myself, I will help out more once I am all settled but I don't really believe it deep down. And it feels good.
In particular, I can't think of anything a child could give away that would fit the "X" in "How are you going to survive without X?"
I also doubt that anyone would remember their actions as a child in such terms. A child doesn't decide to altruistically give away their stuff. It does so because it is in their nature. And as with anything that comes naturally, you are unlikely to form explicit memories of such actions.