how does river song have time lord dna
River Song (Doctor Who) In 2011 series opener "The Impossible Astronaut"/"Day of the Moon", River, along with Amy and her husband Rory (Arthur Darvill), is contacted by a future version of the Doctor to meet up in the United States. As they enjoy a lakeside picnic, the Doctor is killed by an assailant in a space suit, and the trio give him a Viking funeral, in Lake Silencio. In 1969, the present Doctor and company subsequently encounter a little girl (Sydney Wade) who wears the space suit, which River tells the Doctor is a life support unit; the suit has been designed by the hypnotic aliens known as the Silence. Homeless, the girl is later shown regenerating in New York City, 1970. In "A Good Man Goes to War", it is revealed that River is Amy and Rory's daughter Melody (Harrison and Maddison Mortimer[4]), who was conceived in the TARDIS while it was in the Time Vortex and consequently carries Time Lord DNA; the name River Song comes from a recursive translation of Melody Pond via the language of the Gamma Forests; which have no ponds, only rivers; hence the translation of "Pond" to "River." Baby Melody is kidnapped by Madame Kovarian (Frances Barber) to become a weapon against the Doctor.[5]
River Song (Doctor Who) "Let's Kill Hitler" establishes that Melody was trained by the Silence to kill the Doctor. At some point after regenerating in New York, Melody becomes Rory and Amy's childhood friend Mels (Maya Glace-Green) and grew up with them. When adult Mels (Nina Toussaint-White) is shot, and regenerates into her next incarnation (Alex Kingston), she proceeds to do what she was created for: assassinate the Doctor. Persuaded she will one day become River Song, who the Doctor cares deeply about and places in great trust, Melody chooses to resurrect the Doctor with her own regenerative energy, losing any future regenerations. The Doctor learns, however, that it is she who kills him in the future. While she is recovering in bed,the Doctor gives her the blank TARDIS-shaped/coloured diary, and in an epilogue it is revealed that Melody (now River) wants to study archaeology. At the end of "Closing Time", on the day she receives her doctorate, the Silence and Kovarian recapture her and trap her in the space suit in order to kill the Doctor as history will record. In the series finale "The Wedding of River Song", River refuses to kill the Doctor as she is supposed to, creating an alternate reality in which time has frozen and all realities are occurring at once. In order to restart time and repair reality, the two of them must touch. The Doctor marries River and convinces her to repair the timeline by letting her know that he plans to fake his own death and how. River goes to prison for his murder in order to corroborate the deception, though it is established that she regularly breaks out of prison to go on dates and adventures with him with the aid of hallucinogenic lipstick and other tricks.