If the Doctor is the Other it was literally another life. He lived on ancient Gallifrey during the dark time and threw himself into the genetic looms to eventually be born again as the Doctor. Who would be born a baby and have to go to school again.
If the Doctor is just the Doctor he would have to have travelled into Gallifreys ancient history and that would mean he would still be born as a a baby, be a Time Tot go to the academy and then travel back in time to before the academy began.
Either way he still has to be the snotting nosed youth of 90ish who collapsed the Medusa Cascade.
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