In an interview with Playboy Magazine, Sam Houser admitted that he got his mother, veteran actress Geraldine Moffat, to do some voice and mo-cap work for Grand Theft Auto V. While she is uncredited in the game, it is widely believed by many that she played Trevor Phillips' mother. They look similar, her actress is not credited, and she has an uncharacteristically English accent for a woman who is supposed to be Canadian.
Contributed by liquidussnake119