Victims of abuse often lie. Usually they lie to minimize the abuse or protect their abusers.
As a rule of thumb, I would be inclined to believe that, whatever a child tells about how they were abused, it was likely worse than their retelling. Abused children are not generally malingerers. In fact, it is usually the opposite.
So when I hear a child's claims of abuse, I am inclined to not only believe them, but to seek out additional facts about the abuse because children often make it seem less harmful, damaging or extensive than it actually was.