Task: Question Answering
Input (English): Nurse Laura Mattson and World War I military pilot Lt. Geoffrey Aiken fall in love after only knowing each other for a few days. Tragically, he is brought to her hospital and, by chance, put under her care after being fatally wounded on his very first mission. After he dies, Laura realizes she is pregnant. Edward Seward loves her and persuades her to marry him. As far as anyone knows, the child will be his. By 1940, Laura's son Bob has grown into a young man, newly engaged to Peggy Chase. Laura has raised Bob to embrace pacifism. Meanwhile, Edward Seward, now United States Secretary of State, flies home after having negotiated the Seward Peace Treaty, which he claims will make it impossible for any country to go to war again. However, when the U.S. ambassador to the state of "Eurasia" is assassinated while en route to the Eurasian State Department to discuss an earlier diplomatic incident, the President sends the navy across the Atlantic to underscore the U.S. demand for a formal apology. Eurasia refuses to comply, and another world war becomes inevitable despite the treaty. Laura speaks at a large peace rally, over her husband's strong objection. The rally is broken up a group of angry men. A mob then gathers at the Seward home and starts pelting the place. Edward manages to disperse the crowd by first reminding the mob of each American's right to voice his or her own opinion in peacetime, and pledging himself wholeheartedly to the struggle once war is declared. When a news reporter interviews him, he insists his son will enlist. Bob categorically denies this, causing Peggy to break off their engagement. Unable to get his son to change his mind, Edward tells him that he at least has no right to sully the Seward name, revealing that he is not Bob's father. Laura confirms it, and tells Bob of his real father and how he died. 
Question: Who is Bob's father?
Output (English): Geoffrey Aiken