Clown fish epitomize the fact that the way that humans develop in utero into males or females, or the genetics involved in differentiating male from female are not the standard for all living creatures. Clown fish change from undifferentiated immature fish to males as they mature, but only the most dominant in the group is female. If the dominant female is removed from the group, the highest ranking male will become a female in the space of just a couple of months.  Humans physiologically also have the potential to become male or female in the first weeks of their gestation in utero. The inherited chromosomes in combination with hormones shape the development of sex parts in ways that are not always precise.