CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search The Boy or Girl paradox surrounds a set of questions in probability theory which are also known as The Two Child Problem , [ 1 ] Mr. Smith's Children [ 2 ] and the Mrs. Smith Problem. The initial formulation of the question dates back to at least 1959, when Martin Gardner published one of the earliest variants of the paradox in Scientific American . Titled The Two Children Problem , 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? Gardner initially gave the answers 1/2 and 1/3, respectively; but later acknowledged that the second question was ambiguous. [ 1 ] Its answer could be 1/2, d...