I think they were just special abilities, because as you said: the ending reveal surely explains the uniqueness of Jodie's entity. Although, in the Navajo act, after the funeral (assuming you perform the ritual correctly), Jodie goes up into a cave and sees a very similar cave drawing showing that linked entities surely have existed before Jodie and Aiden, lending some possibility of the parents having such a linked entity.
That being said, I still find it hard to see both parents having the same abilities given the following:
- Aiden's unique existence
- Norah being successfully 'put under' (her entity not saving her)
- Norah's entity not killing her (as she expresses her will to have just died)
- Aiden not being able to see Norah's entity in the 'Norah' act. Remember Jodie/Aiden can see other entities of all sorts in every other act (Monsters, dead family members, etc.), so surely he/she would be able to see another linked entity?
- The DPA seems to have not heard of such a case as Jodie's (being linked to an entity), as Dawkins is very curious in their first encounter.
- When Cole tells Jodie about Norah, he makes no statement of the sort: Norah had an entity like Aiden.
After my third playthrough, my answer remains the same.