the body & mind that calls itself "I" exists because it had two parents that had sperm & ovum and the two parents had sexual intercourse at the right time when woman was fertile
as a new born, this body & mind was born like a blank slate but also with certain instincts
however, the 'person', 'individual', 'self' or 'i' we take 'ourselves' to be is something conditioned from the process of 'becoming'
this is why the majority of Europeans consider themselves to be 'Xians' and the majority of Indians consider themselves to be 'Xindus'
the minds 'self-concepts' are conditioned
so back to the original question, the body-mind organism came to exist due to the reproductive mechanisms of parents
