I am one of the people in class who does not know for sure who is the father of Pearl. Even though I'm not 100% certain, there are some clues that Nathaniel Hawthorne leaves that point in the direction of one character. In chapter 9, Roger Chillingworth is sent to take care of Reverend Dimmesdale because he had been feeling ill. I think that Dimmesdale was feeling ill because his heart has been blackened by the sin of committing adultery with Hester and not fessing up as being the father of Pearl. Later in the chapter, Dimmesdale and Chillingworth both move into a house of a widow's. In Dimmesdale's room there are tapestries that show biblical scenes of adultery and its punishment. This is a big clue that I think shows us that Dimmesdale could be the father of Pearl.