My Son Hates His Little Sister and I Don’t Know What to Do

I am a mother of two kids — an 11-year-old son and a 9-year-old daughter. My son and daughter used to get along great when they were younger, but now my son seems to hate her. He scowls whenever she enters the room and refuses to spend time with the family if she is around. He won’t watch movies or eat dinner with us if she is present.

I have tried to talk to my son about why he feels this way, but he just says he doesn’t like her and being around her makes him furious. I understand that they have different personalities, but I…