A single story can lead you to have a wrong perception of a person or group of people. It can be an either good or bad interpretation of this person or group of people but this can have negative consequences. A single story can make you think bad of this person because of one persons opinion. This person can have a bias opinion or just have not had a good interaction with this person but you just hearing their single story can make you form opinions on this person without even hearing their side of things. It is best to hear both sides so that you can come up with a better narrative of the person or situation because with more information, you can be able to come up with a more accurate idea.