They found me deactivated in the remains of a former colony on the planet Omicron Theta. A spacefaring entity had killed all of the colonists. My father managed to escape, but he left me behind.

[Which, I can hold enough of a grudge about that on Data's behalf.]

Before doing so, he wiped my memory of my early development. The first thing I remember now was being reactivated by Starfleet officers who had come to investigate.