By Ken Jennings
(Scribner, $20)

Every child has heard it: Swallow watermelon seeds and fruit will sprout in your stomach. Stick an arm out a car window and a truck will lop it off. In Because I Said So!, Ken Jennings — yes, the famed Jeopardy! contestant — dissects more than 100 tales parents tell children and rates the validity of each. (Answers to the above: false and true.) Jennings also reveals similar warnings from around the world, such as Filipino parents’ forbidding their children to wear red during thunderstorms, as the color is said to attract lightning. The fun lies in the humor Jennings employs as he parses the odd mix of superstition, misunderstanding and scientific fact.