The psychological makeup of one rational animal differs from the psychological makeup of another rational animal even when both are of the same species. These differences are derived from brain chemistry, hormonal differences, reproductive roles, age differences, experiential differences, and education differences, just to name a few. Thus, it should be clear that needs differ from one individual to another within the same species. Observation of our own society brings evidence to bear on this point. Men vote Republican more frequently than do women.
Single women vote Democratic more frequently than married women.
The elderly are more likely to support Democrats than they were when they were younger. One could cynically hypothesize that they are voting purely in their own personal interest, but I believe that there is more to these trends than that. Most elderly individuals have younger relatives. Most women have male family members. It is difficult to believe that they do not take the interests of those whom they love into account when they vote.