You have the concepts of cause and effect reversed here.
Your reward system is a product of the genes you already have. You liking this or that doesn’t effect your genes in anyway, it only matters if the way your genes predispose your behaviour effects your chances of passing on those genes.
Some people would argue that evolution in humans is null. You need a change in environment to drive evolution, humans make their own environment so there is no driving force to benefit this or that gene or alter their chances of being passed to the next generation.