Okay, this one is definitely sad. What if Forrest Gump wasn’t actually the father of Forrest Jr.? If you think about it, Jenny spent the entire movie running to Forrest when she was in trouble because she knew, no matter what, he would take care of her. So maybe when she realized she was sick and wouldn’t be around much longer, she decided the one person who would absolutely take in her son would be Forrest, especially if he believed the kid was his own kin. Horrible? Yes. Manipulative? Yes. But, also just a theory.