How can natural selection be based on genes, if it can even detect genes?
Natural selection cannot detect or distinguish between genes, so it uses phenotypic effects as proxy measures. This the reason why selection looks like it takes place at the level of the organism, and why most adaptations are to the benefit of the organism. However, the idea of gene-based selection is a powerful explanation for many otherwise baffling topics, such as kin selection and reciprocal altruism.
