A friend of mine had 3 children; all lovely, well balanced and affectionate. But one of their grandmother's made it crystal clear that she disliked one of those children. She would knit for 2, but not the 3rd. She took great care to choose the prefect birthday and Christmas gift for 2 but the 3rd was lucky if they got anything at all. She would invite 2 for a sleepover, but not the 3rd. And on it went, with one child being deliberately excluded. The situation was discussed between the parents and GM many times but she simply said "we can't like everyone in life can we?", and carried on as before. As the children grew, all 3 recognised that the problem wasn't with child 3, but with their GM and they simply accepted it and pitied and laughed about her.
GM eventually died and in her will, she left everything, not surprisingly, to 2 GC, excluding the 3rd entirely. But her spite and ill will back fired on her because the 2 "favoured" GC simply divided their inheritance 3 ways, not 2. And GM was never referred to again by any of them.