Back to the Future

The Back to the Future story came from a thought from Bob Gale. Gale discovered in his father's yearbook that his father had been class president. He thought about how he had no affinity with the president of his own graduating class. Gale wondered if he would be friends with his father in the hypothetical circumstance of being the the same age and attending school together. He brought this idea to Robert Zemeckis. Zemeckis thought of a promiscuous girl in high school who, as a mother, told her children she'd never even kissed a boy when she was in high school. They co-wrote the story of the first film in the series.