Why are children not the focus of our preferences?

In biology, all is about the survival and dominance of the species. It would then be logical that we only care about our offspring and its potential to have further offspring. But somehow, evolution made also care about ourselves, in fact we care a lot about ourselves. And lately we care also a fair amount about other species, but I guess modern culture is beyond the survival motive of evolution.

Luis Rayo and Arthur Robson find good reasons why we care about ourselves and how well we consume and enjoy leisure beyond fitness: ignorance. Specifically, think of the relationship between nature and an individual as that of a principal and an agent. The principal can choose the preferences of the individual, but cannot change them in light of transient circumstances. The agent is oblivious to what happens. The preferences need then to include goods that are not the primary focus of nature, for example means to ultimate goals. This is like placing money in the utility function. We do not care about money per se, but what we can buy with it, and the fact that having more leads us to save more. In the case of evolution, liking to sit in the sun makes us create a sufficient amount of vitamin D and makes us fitter for survival and procreation. But now that we know the effect of the sun and how vitamin D is important, we tend to sit too much in the sun for nature's liking. We are too informed for our preferences and should only care about our children.