Any action can become a sin whereby in the process you have hurt someone by what you do. There are twelve sins. Fear, avoidance, gluttony, laziness, pride, deceit, envy, greed, anger, revenge, violence and lust. At first we may not be aware of these for they all start in the mind. If not controlled, these can lead to a habit forming into an action starting from oneself. They become progressive affecting other people in a negative way. What we should know is that all of the twelve sins have one common denominator. Reciprocal. It means that every time it is done, it functions to return to you in one way or the other.
So for example, if you deceive your parents by telling that you need money in order to pay for some school requirements when in fact, you will use the money in other purposes for your personal unnecessary pleasures. Sooner or later, do not be surprised that someone, could be your classmate or your friend, has committed the act of deceit by fooling you which led to your shame and embarrassment.
Another example, when you scold and shout someone in intense anger, it will not be longer when you will realize that you are harming yourself. Your blood pressure may rise which could lead to sickness when habitually done as anger is stored and accumulated. Until one day, you suddenly die of a heart attack.