I believe that Severus Snape is Harry Potter's real father. Now, before you start telling me that it's not true, think about this. When Lily went to Hogwarts her and Snape were best friends despite being in seperate houses, she said that she hated James. Since he was always teasing and picking on Snape. How could she marry someone that she couldn't stand? Unless, she really loved Snape but to try and protect her, they made her marry James.
Which comes to Harry, Snape's really good at potions, Lily's really good at Charms. So why not make a potion to MAKE Harry look like James. Since it's odd that everyone says "you look just like your father, except for your eyes".
Plus if you notice in the movies, James was never close to Lily, Lily made all the moves to be with Harry. James just stood on the side lines, also I know that teachers/professors are to protect their students, but Snape takes it over the lines just to protect Harry.
Tell me what you think, I know that it's out there but that's my theory is that Snape is Harry's real father and James was only there just to protect Lily and Harry since Snape was an agent for Voldemort and Dumbledore