Who is Ben "Sam" Cappadora from The Deep End of the Ocean and what is their importance?

Ben Cappadora (Sam Karras) is three-years-old and described as a precocious, happy, healthy and curious little boy. After his disappearance, we don't meet Ben again until he is twelve, and his name is now Sam Karras. Sam is a very good boy, who's been raised by George Karras to be well mannered, spiritual, responsible and kind. George has provided him with the love and nurturing he wouldn't have received with the Cappadora family. After learning his true identity, Ben (Sam) realizes that he was happier with George Karras, and though he is concerned about the feelings of the Cappadoras, his chooses to return to George.