Rewatching the show, this hit me… and obviously afterwards I see I’m not the first to come up with this idea…
1.) Leela (actor Louise Jameson), Warrior of the Sevateem, was introduced in the 1977 episode “The Face of Evil” as a human member of a tribal society descended from stranded spacefarers. She travels as a companion with The Fourth Doctor (Tom Baker) until “The Invasion of Time” episode.
2.) In her last series scene, Leela tells The Doctor she plans to stay behind with Andred, a Gallifreyan Chancellery Guard commander, with whom she is falling in love.
3.) In the Virgin New Adventures novel Lungbarrow by Marc Platt, The Doctor learns Leela is pregnant with Andred’s child and jokes that she should name the baby after him.
4.) Leela was seen in the promotional short film “Leela vs the Time War” in 2024 fighting Daleks as a Gallifreyan Guard commander during the Time War, moments before using a wayfinder to teleport into The Fourth Doctor’s TARDIS. She announces herself as Warrior of the Sevateem and Gallifrey, implying she has learned a fair grasp of Time Lord technology during her extended life there.
5.) In the 1996 Doctor Who TV movie for Fox (the failed American reboot pilot), The Eighth Doctor tells an Earth woman that “I’m half-human, on my mother’s side.” This line of dialogue has largely been ignored in Who canon (the Doctor does lie a lot), but it could be true.
6.) The 2020 episode “The Timeless Children” explains how The Doctor was found as an infant by the space explorer Tecteun and used to give her native Shobogans on Gallifrey the ability to regenerate their lifespans. This knowledge was saved in the Matrix but erased from the mind of The Doctor. (The girl actor playing the child even has long dark hair, brown eyes, and slightly ruddy skin like Leela was portrayed.) The Master says Tecteun designed the “maximum 12 regenerations” into the version of regeneration given to her people.
7.) Many of The Doctor’s lives before The First Doctor were erased or repressed, as seen in the psychic duel of “The Brain of Morbius” and later stories.
8.) Some Doctor Who extended universe media say a figure called The Other, someone with a hidden identity, helped Rassilon found Time Lord society.
Having Leela and Andred be The Doctor’s true birth parents fits the shown facts, assuming Leela sends her baby back in time, perhaps to avoid the coming horrors of the Time War. (“We see further back, the Timeless Child… We see what’s hidden even from yourself. The outcast, abbandoned and unknown…”) The child is physically like his father and other Gallifreyan Time Lords, but he retains the wild spark of humanity from his mother. This reveal would also support why The Doctor hangs out with humans so much and became so protective of their homeworld.
Possible follow-up questions…
1.) Sometime between The First Doctor (William Hartnell) and The Seventh Doctor (Sylvester McCoy), how does The Doctor learn of his own genetic hybrid nature, even if not knowing his birth parent’s true identities?
2.) Who does The Doctor think raised him as a child, since memories of Tecteun and Division were erased?
3.) If The Doctor knew he/she was half-human all along (at least since The Eighth Doctor), why is The Thirteenth Doctor (Jodie Whittaker) so incredulous when learning the whole story from the Master in the Matrix?
4.) What became of the older Leela after she escaped back to The Fourth Doctor during the Time War? (Might she have told him the truth then?)