Four-year-old Sam and two-year-old Marie have breakfast with their dad. Sam stretches his legs out, and touches the legs of Marie’s chair.

Marie: Stop it Sam, that’s my chair.

Sam: I just need to stretch.

Marie: Daddy, Sam’s touching my chair.

Dad: Marie, it’s okay. He’s not bothering you. But Sam, if Marie asks you to stop, it would be nice if you stopped.

Marie kicks Sam and starts screaming. Sam starts screaming. Two minutes later, they calm down.

Marie: Dad, you’re giving me a headache.

Dad: I’m giving you a headache?

Marie: Yeah.

Dad: Why?

Marie: Because you’re a problem.