In Nature, family members don't mate with each other. And yet
they help each other to survive. Do you know why? It increases the
chance that their genes will be passed on to a new generation.
Altruism among blood relatives is a response to natural selection.
It's called the Selfish Gene Theory.
They don't? I thought this would be quite common in polygamy society.
Anyway, the exsistance of altruism is unexceptionable.
我曾经听说过有一种耗子会无偿抚养自己兄妹的后代