Among knitters there is a widespread belief in a superstitious phenomenon known as the “Sweater Curse”: a belief that if the knitter gives a hand-made sweater to a significant other it will lead to a breakup; in a 2005 survey, 15 percent of hobby knitters said they had directly experienced it and 41 percent took the superstition seriously.
Source: How To Geek
Curses are all about belief in them. A curse works on faith and fear of that faith. It is scary to believe in something. Partly because that means there really is something bigger and more powerful than yourself. No wonder there are so many religions. I think early people needed all the options they could get. Do something one god/ religious party disapproves of and you need to rely on another to protect you from the ill will surely being sent your way. Curses from your former co-believers. It's all interesting, religion always is.
Create a curse.
What is the story behind it? How did it get started? Why do people believe it and how does the belief keep going? What evidence is there to show the curse is real?
As for the sweater curse... can you prove it wrong? Do you knit?