" Walli’s sister came into the room. Lili was almost three years younger, and these days he was not sure how to treat her. For as long as he could remember she had been a pain in the neck, like a younger boy but sillier. However, lately she had become more sensible and, to complicate matters, some of her friends had breasts. "

― Ken Follett , Edge of Eternity (The Century Trilogy, #3)