The boy or girl paradox surrounds a set of questions in probability theory, which are also known as the two children problem, Mr. Smith's children and the Mrs. Smith problem. The initial formulation of the question dates back to at least 1959, when Martin Gardner featured it in his May 1959 "Mathematical Games column" in Scientific American. He phrased the paradox as follows:Mr. Jones has two children. The older child is a girl. What is the probability that both children are girls? Mr. Smith has two children. At least one of them is a boy. What is the probability that both children are boys?