...are your kids capable of just ignoring each other?

My son sometimes bothers my daughter and she will come running to me and say, "He's bothering me!!" But when I tell her to just ignore him, she looks at me like she has no idea what I'm talking about. She feels she HAS to respond to his questions and comments, even if she doesn't want to.

Not sure how to teach a kid how to ignore someone... but my kids need to learn this life skill!