I've done research for articles about bullies, and it's now known that (contrary to the popular notion that they're insecure, frightened, kids "on the inside") bullies tend to be narcissistic and to be kids who have either experienced or witnessed violence in the home. Of course, not all bullying involves physical violence. There's such a thing a verbal bullying too. Bullies don't respect other kids (obviously), and kids learn to respect others by being respected themselves (and seeing respect "in action" when parents treat them with respect).
So, my answer to this question would be 1) don't bully your children at home (and don't let siblings bully them either), 2) treat them with respect (it's possible to tell kids right from wrong, and to impose consequences for negative behavior, without treating them without respect), and 3) if they act as if they don't respect someone else, or act as if they think only their own feelings matter, point out to them why that behavior is inappropriate and tell them what appropriate behavior would be.