Morals, beliefs, faith forms an important part of one's personality, however, people always forget the grey area; Oxford defines superstitions as "excessively credulous belief in and reverence for the supernatural" Simply speaking, it's just an irrational belief. The number 13, black cats, broken mirrors, crossed fingers are all walking examples of our irrational beliefs. But if they are not scientifically proven and are simply unfounded and irrational, then why do people believe in the unbelievable. 

This might have to do something with our upbringing. We are brainwashed to always take fewer risks, to remain on the safer side. And this mindset sets the perfect environment for the seed of superstition to grow. People start to fear fears and try everything in their power to keep the demon off the edge. They forget that life's true meaning lies within our perils and hide behind the curtains of what we call superstitions. 

To avert anything wrong to happen in their life, most people already take every preventive measure in the disguise of superstitions. However, this affects a person's mental health in more ways than one. They stop taking risks, they tend to take every overcalculated step and in a great way relieves a person's anxiety...or as that person likes to thinks so. They also produce a false sense of having control over conditions. 

Besides all of these reasons, superstitions weren't given to us a gift from our forefathers(some are considered to be) but they mainly develop over time and are prevalent in conditions of absence of confidence, insecurity, and threat. 

"I think life is a series of random coincidences and can't be shaped by these strange little habits, but I guess it's reassuring to believe you have some control over it - especially when there's so much about our lives and society that we can't change"