Before the likes of Michael Myers and Freddy Krueger donned their slasher personas, the evil that fueled them was a part of them on a deep level. But in the case of Jason Voorhees, his murderous tendencies were more nurture rather than nature, thanks to his twisted and violent mother, Pamela Voorhees. However, not much was known about Jason's past aside from what Pamela described in Friday the 13th. There were moments when Jason's behavior would signal classic signs of abuse that were either a result of or resulted in some of his biggest issues.
Source:https://www.cbr.com/jason-voorhees-mom-source-deepest-traumas/