It's simple, really...... these folks (the old people) are in the early stages of some form of dementia (Alzheimers, etc.); one of the major early symptoms is a dramatic personality change, and it sounds like this is happening big-time......... and the way the kids are acting, simple....... denial........ they are in denial that the problem lies in their parents, and are instead siding with them and misdirecting anger to you........... the same thing happened with my grandma..... she was losing her mind, and none of my uncles or my dad wanted to believe it, so they were blaming the problems I was having with her on me (I lived with her and took care of her)......... She is now in assisted living, as her mind was really bad and she couldn't be left alone AT ALL............ but in the early stages, she just wasn't "herself", i.e. she never swore, but she started to, etc.