Here are some strategies that may help:
Set clear boundaries and expectations: Let your child know that it is not okay to be mean to their sibling and explain to them the importance of kindness and empathy.
Encourage positive interactions: Set up opportunities for your child to interact positively with their sibling, such as playing together or reading a book together.
Role-play: Use role-playing to help your child understand and practice appropriate behavior with their sibling.
Teach empathy: Help your child understand how their sibling may feel when they are being mean.
Positive reinforcement: Praise and reward your child when they show kindness and empathy towards their sibling.
Show them how to express their feelings: Children at this age may not yet have the ability to express their feelings in an appropriate way, it's important to teach them how to do it.
Get professional help if necessary: If the problem persists, seeking professional help may be beneficial. A child therapist or counselor can help the child develop healthy coping mechanisms and understand the reasons behind their behavior.
It's important to approach this situation with patience and guidance, providing positive reinforcement when they show kindness and empathy towards their sibling.
Remember, children at this age are still developing their understanding of the world and may not yet have the ability to express themselves effectively.