Doctor Who: 10 Things We Actually Know About The Doctor's Family
2. Their Biological Family Is From Another Universe
As mentioned, it was recently revealed that the Gallifreyan explorer Tecteun discovered the Doctor – then known as the Timeless Child – abandoned at a monument beneath a wormhole.
Tecteun adopted the child, but as a science experiment rather than out of any sort of maternal love. She spliced the child's DNA into certain Gallifreyans to give them the secret of regeneration, and naturally, discovering this genetic gift gave Tecteun a degree of power and influence in the early days of Time Lord society.
But where does that wormhole lead, and where does the Doctor originally come from? Well, as stated by Tecteun in Flux, the other end of the wormhole leads to another universe, meaning that the Doctor isn't just from another planet – they're almost from another reality.
So while the Doctor may have had siblings, uncles, and mothers, these were all part of their adopted Gallifreyan family. Their true biological family – if they're still around – lies in the next universe.
Alternatively, given how little we know about the Timeless Child's species, maybe they just spring out of the ground, or are grown in a lab. It's possible that the Doctor has never had any biological family at all, which could be subconsciously fuelling their innate desire to bring home so many strays.