Most already know the impact Uncle Ben had on Peter Parker's decision to become a responsible costumed crime fighter. When Uncle Ben was murdered at the hands of a criminal Peter could've used his powers to apprehend earlier on, the guilt compels him to use his newfound abilities as a force for good.
Aunt May basically raises Peter as her son over the course of his costumed career. She takes care of him all by herself after the murder of her husband, Uncle Ben, and the disappearance of Peter's natural parents. She has no clue of Peter's second life as Spider-Man....or at least she doesn't let on that she knows. Later issues of the comic revealed that she was aware all along. Aunt May has been killed off and brought back to life, but for the most part she is the one constant in Peter Parker's life.
