Doctor Who: 5 Questions Raised By The Series 12 Finale

5. Why Can River Song Regenerate?

In 'A Good Man Goes To War', the Doctor and Madame Vastra discuss why Amy and Rory's daughter Melody (who grows up to be River Song) has Time Lord elements in her DNA. They quickly deduce these elements are present because she was conceived while the TARDIS was in the vortex. While it took billions of years for exposure to the time vortex to introduce these mutations into Time Lords, with Melody it happened immediately.

Later episodes establish that River can, in fact, regenerate. Even though she used up all of her remaining regeneration energy to save the Doctor in 'Let's Kill Hitler', she still possessed a lifespan that was far longer than the average human.

However, 'The Timeless Children' contradicts the information revealed in 'A Good Man Goes To War', saying that Time Lords gained the ability to regenerate due to gene splicing that ability from the Timeless Child into themselves. If this is the true origin of their regenerative abilities, then why could River do it without the gene splicing?