Otherkin are a subculture of people who believe we are nonhuman. We know our bodies are physically human, but in our minds or our spirits we are something other. There is a feeling within us that we don't belong to the species we are born as, maybe that we are born in the wrong body, or existed as a different creature in a past life, or that our brains are wired to be other than human; and that is just a few things on what it means to be Otherkin. It is important to understand that we don't choose to be this way, and that our identities are inherent to our nature. One can not become Otherkin, they simply are or are not.
More or less, most believe one needs to be born Otherkin. Even if we don't necessarily know this about ourselves right away, or don't awaken to it fully until we are older, it is defined as something part of us that was always there. Its in the little details that make up who we are and what we experience as nonhuman; things that often go unnoticed until that revelation is had. An awakening, the moment of realization, is not a sudden change in a person, it is acceptance of what has always been part of who they are.
Commonly, Otherkin identify as creatures of myth, fantasy, or sci fi origins. Dragons, Elves, and even Aliens are examples of some of the people who make up our community. Of course, some Otherkin identify as Earthen animals, but they are usually referred to as a Therian instead and stick to the Therian Community.
Why we are this way, you will find, varies from one Otherkin to the next. There are those of us who find spiritual belief's to explain their Otherkinity, and others who have come to believe in rather a psychological reasoning behind it. All the while we are still experiencing the same phenomenon that makes us Otherkin, which is believing we are nonhuman.
Some of the things that are common to Otherkin are not equally shared by every individual. Some have memories of past lives, and others do not. Some experience phantom limbs(the sensation of ghostly limbs such as tails, wings, or snouts), and others do not. These things, that lots of Otherkin do experience, are not a requirement to consider oneself Otherkin. There are many kinds of Otherkin with their own unique experiences, making one Otherkin not quite like the next. Still, we share the common ground of believing ourselves to be fully or partially not entirely human.