As a child, Alfred Hitchcock had a strange relationship with his parents. His father had him locked up at a local police station when he would misbehave and his mother would force him to stand at the foot of her bed and reveal to her all of his wrongdoings at the end of each day. His feelings towards his father were not good ones and the relationship with his mother was uncomfortably intimate. These odd exchanges with his parents may have been the inspiration for the unusual family dynamic in many of his movies including Strangers on a Train.
One of the main characters in Strangers on a Train is named Bruno. We see early in the film that he, like Hitchcock, has a very close relationship with his mother. His mother is also well aware of his hatred of her husband.
Later in the film, when he meets the other main character, he asks Guy to kill his father for him. These feelings might not have been so far from what the director wished for his own father. In Hitchcock’s Films Revisited, Robin Wood writes about a Freudian theory called the Oedipal Complex. Wood suggests that Hitchcock uses a theme called repression in this films because of his homophobia. Freud said that in one stage of psychosexual development, a boy will develop a desire for his mother and a competitive and jealous feeling for his father. One could argue that Bruno never passed this stage in his development which explains the intimate relationship he shares with his mother and his desire for his fathers demise.
Wood, Robin. “Murderous Gays: Hitchcock’s Homophobia.” In Hitchcock’s Films Revisited, 338. New York: Columbia University Press, 1989.