All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Children are often the victims of the evil eye, not its source. After research and investigation, we could not find any mention of a case in which a child casts the evil eye on a person. However, it cannot be ruled out. Casting the evil eye on others does not necessarily indicate that the doer is evil; it may sometimes happen when a person casts a look of admiration or the like, as scholars have explained.
What is mentioned in the question about this nine-year-old boy may have nothing to do with the evil eye in the first place. He merely wished that his parents would get a divorce; this is a sort of supplication that may or may not be answered.
The behavior of this child mentioned in the question, especially his misconduct toward his parents, the cause of it should be investigated and action should be taken to treat it. Please refer to Fataawa 85041 and 237535 about the guidelines for parents in raising their children in order to prevent them from being undutiful towards the parents and how to treat children's stubbornness by being with them, supplicating for them and encouraging them to be dutiful to their parents. It should be highlighted that the Ruqyah is effective for children in all cases - Allaah Willing. For more benefit, please refer to Fatwa 4678.
Parents are also advised to complement each other's roles in the way they handle the child. The father should generally be firm and serious and may resort to appropriate physical punishment if needed. The mother should generally be lenient and gentle and should beware as much as possible of being aggressive or reproachful as that may make the child feel some hatred for her. For further benefit, please refer to Fataawa 85764 and 87009 about the limits of physical punishment in disciplining children.
Allaah Knows best.