Two ant colonies A and B. Sugar is abundant in the area and all ants in colony B prefer sugar. 95% of the ants in colony A prefer sugar while 5% prefer peanut butter. The ants that like peanut butter have a higher risk of getting killed because peanut butter is scarce and they must travel further. They also use more energy in getting food. One day a truck drops sugar near the colonies that is poisoned. Colony B is wiped out. Colony A survives on because of the 5% of ants that prefer peanut butter. The queen may die but the surviving ants reproduce.

We all know someone who hates a particular food that most people love. We all know someone who loves a food we think is disgusting. Why don't we all like the same healthiest foods?

I'm not an expert on genes but it's possible that in one species, taste or some other variable is determined by 1 or 2 genes. In another species it may be determined by 8 or 9 genes. This complexity in taste determination may cause more variation in how it manifests. Maybe that complexity causes odd variations to occur over generations. Even as other factors select for sugar in one species, individuals keep popping up that like peanut butter.