Since cultural factors and ideas are not genetic, they can't be explained (not even in principle) by natural selection and hence evolution. I wonder why scientists pretend not to see this obvious fact.
Our cultural features are an outgrowth of our genetic heritage. We evolved to be social beings, to have one mate (although this trait is not as strong as in other species), to invest a lot of effort into our offspring, etc. Our cultures reflect these genetic imperatives. However, there are a variety of cultural behaviors that can manifest which are different from each other yet still function to fulfill our biological imperatives.