Podkayne -

"I’m not checking the navigation, you little monster," Podkayne replied, though her voice lacked any real bite. "I’m looking at the stars. I am going to command a ship like this one day, Clark. A real exploration cruiser. Not just a luxury liner filled with tourists who think Martians are practically savages."

Classic Sci-Fi Review: Podkayne of Mars by Robert A. Heinlein podkayne

Podkayne whipped around, her red hair catching the harsh glare of the dome's artificial lights. "Babies need individual attention, Clark! Just because you were born with a block of ice where your heart should be doesn't mean the rest of the galaxy is like that." "I’m not checking the navigation, you little monster,"

Clark made a noise that was halfway between a grunt and a sniff. "To do that, you'll need to master third-order differential equations, Poddy. Last night, you spent two hours trying to explain to the nursery attendant why babies shouldn't be kept in centralized crèches." A real exploration cruiser

"You’re staring again, Poddy," Clark said without looking up. His voice was flat, devoid of the childlike wonder that usually occupied eleven-year-olds. "The trajectory hasn't changed in the last forty minutes. We are still falling toward Venus at exactly the planned acceleration."

Behind her, the gentle clicking of a pocket computer signaled that her younger brother, Clark, was being brilliant, anti-social, or most likely, both.