Donna is six when Rose gets pregnant again. Both of them are ecstatic, of course, and Donna is desperate to have little sister when they tell her. Rose looks her daughter in the eyes, sees her father's mischief there, and sees a little girl being tormented by her red-headed older sister, sucking her thumb, and with two adorable blonde pigtails.

She can't wait, and neither can Chris - this isn't planned (nothing ever is), but they'd never turn down something like this.

Only when they get to the Doctor's this time there is something more surprising awaiting them.

Two heartbeats.

This time it's twins.