A dog trainer who loses their temper teaches the dog to dread training. How you correct matters as much as what.

How a correction is delivered teaches more than the correction itself. An animal, or a person, learns to associate the whole situation with the way it felt, so an angry lesson teaches dread of lessons rather than the thing you meant to convey. Accuracy of content does not survive the manner. You can be entirely right and still be teaching the wrong thing.

When you next have to correct someone, a younger sibling or a teammate or a pet, deal with the behavior and leave the temper out of it. If you are already angry, wait the few minutes until you are not.