However, they play a key role in the formation of personal identity. Humans, as a member of the mammalian class, are one of the few species that raise their young. According to the National Wildlife Federation, fewer than ten percent of all mammals raise their young. This means that parents of less than ten percent of mammal species teach their children the skills of survival and social acceptability. The majority of humans raise their children to be polite, educated, and socially accepted, according to society's norms. As we grew up, life changed us and shaped our character and way of thinking. Our thoughts are not our own, they are based on influences from our environment and others. For example, if a teenager is raised by parents and has friends who are fans of the New England Patriots, there is a good chance that when the teenager becomes an adult, that person will most likely have a positive bias for the New England Patriots. As children grow up, they are sent to school to learn and regurgitate what society has accepted as truth. People's thoughts are shaped by their environment and upbringing and are therefore not their own.