Some multiples have had the experience of others sharing the body with them since birth, whether or not they were traumatized in any way. (Some remember being multiple before they were abused, or being abused or punished because they were multiple.)
Many such multiples feel that plurality is simply a natural variant of the human mind-- something which, like sexual orientation or gender identity, is either inborn, genetic, or hardwired in at such an early age as to make changing it later in life impossible.
Others have offered spiritual explanations for their multiplicity. Some see multiplicity as the result of persons from past lives sharing one's current body. Others see it as the result of having channeled someone in before birth.
A few multiples who see themselves as being in the DID trauma/splitting model believe their multiplicity was the result of trauma suffered before birth.
Page constructed with contributions from Shiu of Amorpha.