"I thought you said it was all right if there couldn't be kids."

"Well, yeah, I did, but I didn't say it wasn't all right if there could. And it's not like you're going to raise me, or anything like that, so it's actually a perfectly valid psychological condition that's even recognised by your backward lot."

"But... I can't be your mother! I'm only nineteen!"

The Doctor got the feeling that Rose still didn't quite understand this whole time-travel lark.