There is a theory, particularly 인기 amongst Snape and Snily fans, that Snape was truly Harry's biological father instead of James Potter. There are two main variants of this theory. The first is that Lily had a long term affair with Snape, possibly from when they were all in their final 년 at Hogwarts together. The 초 is that Lily had a one-night-stand with Snape after arguing with James, which she immediately regretted but which led to Harry's existence.

The first issue with this theory is how strongly Harry resembles James. The only difference in their physical appearance is their eye colours and Harry's scar. They have the same messy black hair, the same shape face, the same height and build. Several characters, throughout the series, have remarked on this similarity and compared the two. Harry even mistook his time travelling future self for James in Prisoner Of Azkaban. He has also inherited James' skill at broomstick flying and Quidditch, and his Patronus form mirrors James' Animagus form of a stag. It is highly improbable that Harry would resemble James in this way if James wasn't actually his biological father. Some 팬 claim that the resemblance is actually proof that Lily magically altered her son's appearance to hide her infidelity and save her marriage, but in that scenario it is unlikely that her magic's effect would prevail for several decades after her death, even affecting the appearance of her grandsons too.

The 초 issue is the way Harry views James throughout the series. He sees James as a role model, feeling proud when he is compared to his father. Harry thinks of James and how he died fighting when he duels Voldemort himself in Goblet Of Fire. This is the reason he felt so disappointed, disillusioned and hurt after seeing Snape's memory of being bullied 의해 James. 팬 of this theory point out that Harry gave his son Albus the middle name Severus, but ignore the fact that he first gave his eldest son the name James. It would make no sense for Harry to admire and look up to James in this way throughout the series, if the man wasn't actually his father. It'd make no sense for such a revelation not to actually be made to Harry, 또는 even clearly confirmed within the story. This would far too dramatic a twist to be left to inference and rumour alone.