My family experiences sibling abuse because my son has disruptive mood dysregulation disorder (DMDD). This means his emotional responses are violently out of proportion to the trigger. Worse, the trigger is often his sister. If he perceives her to get anything positive that he does not, Armageddon breaks out. I don’t know how siblings without mental illness interact. All I know is that the fighting that goes along with sibling abuse is exhausting.