A lot of people don't believe in curses. A lot of people don't believe in yellow-spotted lizards either, but if one bites you, it doesn't make a difference whether you believe in it or not.

This is a statement from the narrator which implies that regardless of whether Stanley's family or the reader believes in curses, the bad luck that they are the recipients of is undeniable. And, just as the lizard's bite is deadly, so is the supposed curse that Stanley's family is under.