According to Biography.com, Issac Newton never married. Although he became very famous and quite wealthy, Newton had few personal friends. The University of Florida suggests that, perhaps partially due to his upbringing, he had a complicated and often difficult personality.
Biography.com states that Newton's mother was pregnant with him when his father died. When the boy was 3, his mother remarried and left to live with her new husband. The young Newton was left in the care of his grandmother until his stepfather died. At 12, Newton began living with his mother and three step-siblings. Biography.com indicates that the prolonged maternal separation had a tremendous impact on Newton throughout his life, leaving him extremely insecure.