I have a boy and girl twins and they still fight. They will be 8 this year and it does not get better. They scream at each other constantly and physically fight, but yet they still sleep together. There will still be some kind of bond between them, but I was told by child psychologists' that it is normal, they are fighting for individulality. so I hope it get better for my sake and I wish you luck. Your kids are 3, you still have a long road ahead of you..