Martian Child

Martian Child is a 2007 American comedydrama film about a writer who adopts a strange young boy who believes himself to be from Mars. Martian Child was released on November 2, 2007. The film was directed by Menno Meyjes and produced by New Line Cinema. It stars John Cusack and Bobby Coleman.

With the help of Davids friend Harlee Amanda Peet and sister Liz played by Cusacks real life sister Joan, David and Dennis begin an arduous process of learning about each other, from Denniss incessant phototaking habits, his inclination to eat only Lucky Charms, and his perpetual stealing, to Davids continuing love of his wife, his love of baseball and his own struggles to be accepted by others.As David teaches Dennis how to be an Earthling, father and son earn each others trust and eventually find someone who will love them unequivocally. ........

Source: Wikipedia