The Selfish Gene: Why are people?

I was kind-of confused when reading the first chapter of "The Selfish Gene". It's interesting but I'm not used to read these scientific-investigation themes (if it classifies as one). What immediately attracted my attention were the two main points of the book: altruism and selfishness.
"Before going any further, we need a definition. An entity, such as a baboon, is said to be altruistic if it behaves in such a way as to increase another such entity's welfare at the expense of its own. Selfish behavior has exactly the opposite effect", (Dawkins, pg.4).

It was surprising for me that someone would be interested -as stupid as it seems- in such a thing as a gene. I know that without people being interested in this we wouldn't know anything of ourselves, but what I mean is the fact that someone characterizes a gene as 'selfish'.

After reading the whole chapter I realized that although it's strange, it's a brilliant investigation on a human's behavior. I agree with the selfishness within us, how we think first in us than anything; an instinct of survival. Instead, altruism -as said in the definition- is totally different. At this point I think we are altruistic but not naturally; not everyone posseses it. We can if we want, it's something we can control, when selfishness comes harder to...