Trivia: (POSSIBLE SPOILER) When Masuka brings up the list of doctors authorized to get the M99, Dexter removes his alias note that Dexter's fake alias (used to get the M99 tranquilizer) is Dr. Patrick Bateman. Patrick Bateman is the lead character of "American Psycho". This was most likely an intentional "easter egg" of sorts within the show.
Trivia: Michael C. Hall and Jennifer Carpenter, who play siblings on the show, were actually married in real life, from 2008 - 2011.
Trivia: When Dexter is looking at Isaak Sirko's file on his laptop, the top picture on the column of three is a screenshot of Ray Stevenson in Punisher: War Zone. (00:23:58)
Trivia: In this show, Christian Camargo plays Dexter's older brother. In real life, Michael C. Hall is 5 months older than Camargo.
Trivia: When Dexter and Rita return home from their date, Deb tells Rita that her daughter, Astor, nearly made it through Saw and Saw II while she was babysitting her, which elicits a concerned look from Rita before Deb states she was joking. Julie Benz, who plays Rita, appeared in Saw V, which was released 5 weeks before this episode first aired.
Trivia: Michael C. Hall was wearing a wig during the whole fifth season after battling cancer until early 2010.
Trivia: When Deb is telling Dexter that she has a date with Lundy that night, she remarks that he is 20 years older than her. In real life, Keith Carradine is 31 years older than Jennifer Carpenter. (00:22:30)
Trivia: John Lithgow revealed in an interview with GQ that he initially turned down the role of Arthur Mitchell, a.k.a. the Trinity Killer. He was convinced to change his mind by his agent and his lawyer. He ended up winning an Emmy for the role, so he definitely made the right choice.
Trivia: Some notable differences between season 1 and "Darkly Dreaming Dexter" - the first novel in the series of books that the show is based on - are that Deb and LaGuerta both discover Dexter's secret by the end, which doesn't occur in the show until seasons 6 and 7, respectively. LaGuerta is also killed by Brian, a.k.a. the Ice Truck Killer, whose true identity isn't revealed until the last chapter, and he is also referred to as the Tamiami Slasher. He also escapes at the end of the novel.
Answer: No, Harry is not the real father. While he did have an affair with Dexter's biological mother (Laura Moser), this was when she was his C.I. Dexter was already born at that point.