Is Snape really Harry’s father?
No, Snape is definitely not Harry’s dad. James Potter is Harry’s dad. There is no chance that there is ambiguity or mystery here. Snape was a rival for the affections of Harry’s mom (Lily).
Can Harry be Snape’s son?
Not at all because harry resembles james potter(though he has green eyes of his mother) and is patronus is a stag. Harry’s patronus is a stag and Severus Snape’s is a doe, so they’re quite different and Harry looks like his father which is why Severus hates him.