@Curiouschlo if the incident in Sheffield is the one I think you're referring to, it was rather more complicated and tragic than "crazy mother tries to kill her children".
The woman in question had been horribly abused by her family as a child and teenager. She was presented by the media as being in an "incestuous relationship" with her older half-brother, who was also abused as a child and in all probability was one of her abusers too. Personally I doubt this "relationship" was consensual but that is speculation on my part.
Given her history, it is unsurprising that she had severe mental health difficulties. In court it emerged she was terrified of her children (which were possibly her half-brothers) being taken away from her.
She was failed awfully by the state when she was a child herself. Who knows what crimes the surviving children will go on to commit? Hopefully none, but sadly, cycles of abuse are extremely difficult to break and trauma begets trauma.
It is a strange contradiction that the same children who are abused and who elicit nothing but sympathy will then grow up and become "evil" and deserving of not one iota of compassion.
I'm not excusing what she did, but you need to read and engage your thought processes past the headlines in the newspapers.