Where do little children come from?' This is an embarrassing question,” admitted Jean-Jacques Rousseau. Best, he thought, was to hope your kid doesn't ask it. But if the question does come up, Rousseau advised in 1762, answer it “with the greatest plainness, without mystery or confusion.” The important thing is to avoid having this conversation with your kid during the impossible years. Wrote Rousseau: “If you are not sure of keeping him in ignorance of the difference between the sexes till he is sixteen, take care you teach him before he is ten.”