I think a lot of disorders can cause intrusive thoughts. Have you been formally dxd with OCD? If not you should probably see a dr.... you mentioned family / early childhood trauma possibly sexual. PTSD often causes intrusive thoughts. Also many ptsd symptoms can overlap ocd like symptoms and if resulting from early childhood traumas, from my personal history and many other sources, can result in the development of more than one sometimes many comorbid disorders...esp if the trauma was not addressed and treated early. Which sadly is far to often the case for many children. Hope you find a path to healing and support here.