Did you all read the full article? The mother's IQ is 77.
While what she did is, obviously horrible, I don't think she has the capacity to see what was wrong. Her "borderline" mental capacity makes it a wonder than either of her other children managed to survive to their 20s, but even they didn't make it unscathed.
I would wish no evil on this woman, I would merely hope and pray that she never, ever, ever, reproduces again. She is, quite apparently, hardly able to take care of herself.
I call Hanlon's Razor. "Never attribute to malice that which can be adequately explained by stupidity."