Fourteen-year-old actress Marsai Martin, the star of the TV series “Black-ish,” is also one of the youngest executive producers in motion picture history. Her company, Genius Productions, is behind the new comedy “Little,” a sort of reversal of the Tom Hanks classic “Big,” in which an overbearing professional woman is transformed into an adolescent – an example of Martin proving that you can do anything at any age. Nancy Giles chatted with the young mogul, whose parents are trying to make sure she doesn’t grow up too quickly.