The Doctor goes up to the comm room to talk with the Silurian. Dorium is at the control panel. Vastra gently chides the Doctor for his display of anger earlier. She reminds him that he once told her that "anger is the shortest distance to a mistake" when he first found her, trying to avenge the death of her sisters on innocent men. Then she gets to the real reason she called him: "Is Melody human?" "Of course she is!" the Doctor says with just a little too much surprise. "She's completely human! What are you talking about?" Dorium pulls up scans of Melody's DNA. She's human, with a little Time Lord mixed in. The Doctor gapes at the computer screens.
Meanwhile, Lorna is protesting her innocence. She says she heard Madame Kovarian talking about a trap. They're distrustful of her. She insists she only joined the army to meet the Doctor. "How else do you meet a great warrior?" Amy stares. "He's not a warrior," she says. "Then why's he called the Doctor?" Lorna asks like it makes perfect sense. Before anyone can answer her, the lights start going off.
The Doctor is insisting that Melody is human. "She's Amy and Rory's daughter!" They babble about how the Time Lords evolved after being exposed to the Time Vortex and debate about whether or not Melody might be able to regenerate. Vastra tries to very delicately ask the Doctor when any rampant screwing may have occurred on the TARDIS, but the Doctor is a bit obtuse. I remember the time I had to explain to my grandma a joke about kneepads and oral sex. Old people are just not hip to these things. He finally does get the point, though, even though he's supremely uncomfortable. Vastra asks if the child could have been conceived on the TARDIS, in the Time Vortex. "No! No, impossible," insists the Doctor. "It's all running about and sexy fish vampires and blowing up stuff and Rory wasn't even there at the beginning!" The Doctor keeps talking until he talks himself into realizing that it must have happened on Amy and Rory's wedding night.