He starts bullying his siblings
Children who are being bullied can bully their siblings as a form of compensation and imitation of what they see as well, a child against his younger siblings may be an indication of what exposed.
The role of parents
If your child is being bullied, it is so important to stand by his side. Start by listening and empathizing with what he is going through, and then think about how to handle the situation better. Of course, reporting bullying that occurs in school is always the best option, but you must make sure that your child wants it.