Selfish Gene

I think evolution in terms of natural selection through genes is the less important aspect of how humans develop and behave nowadays. Noone has to fear to be killed because of his genes (through whatever process) and the genes effect on the likeliehood of having children is really small. What has a way greater impact on us is the family and environment we a born into, the way we are educated, the moral values we are taught. These things will determine whether you will possibly marry someday and have children. So any explanation of altruistic behaviour purely by the means of our genes lacks these major cultural and social influences.

Whether you believe in morality is totally your choice. But even if you don’t you will probably still act as if you do since our society encourages moral behaviour and punishes the opposite (not only by law). The question is what you would do if you had the chance to act immorally for your own profit if you didn’t have to fear any kind of consequence. But this is mostly a theoretical question since you rarely encounter such situations.